Seven Bowls: please explain

This song deals with two different passages from the book of Revelation. 

The first follows the description in Revelation chapter 10 of a little scroll that and angel told John to eat. It concerns two witnesses who are introduced in chapter 11 of the book of Revelation. There is an interesting suggestion that they represent Moses (and his Law) and the Prophets.

The other passage dealt with in this song is the Seven Bowls of Wrath judgments in chapter 16 of Revelation.  As I have suggested previously, this may well be a description of the Day of the Lord from a non-Jewish (gentile) perspective
(Just to help you get your bearings, the songs about the Dragon and the Beasts are culled from Revelation, chapters 12 and 13. Chapter 14 is a reprise of the prelude to the Seven Trumpets, once again talking about how the promises God made to Abraham are to be fulfilled. And chapter 15 is a prelude to the Seven Bowls)
Well there’s to lamps burning oil and shining bright - There’s two witnesses attesting to the light
Light atonement’s sorry plight,
Redemption’s joy ignite - Bearing witness, burning oil and shining bright

Does that make any sense to you?

It might if you had read the book of Zechariah.
Be grateful I did not give you the Zechariah version. He was the Old Testament prophet who told the remnant of Jews who returned to Jerusalem from the Babylon captivity that they had to rebuild the temple. 

John seems to borrow a lot of the images he uses in Revelation from Zechariah, so let’s go to the source...
Zechariah’s fifth vision - the lamp stand as a symbol of the word of the Lord to Zerubbabel
In Zechariah 4: 2-3 there is a vision of

1. a lamp stand all of gold, with a bowl on the top of it, and...
2. seven lamps on it, with seven lips on each of the lamps which are on the top of it... and 
3. two olive trees by it, one on the right of the bowl and the other on its left."
Zechariah was mystified. How about you?
The angel tells him it is the word of the Lord to Zerubbabel! Still mystified?

Zerubbabel was the leader of the exiles appointed by the Emperor of Persia to lead to Jerusalem the remnant that was to return from Babylon and rebuild the temple in Jerusalem. (Nehemiah would come later to build the walls around the city to ensure the temple would be safe) 
Still confused? Clarence Larkin provides some help in his book on Revelation. (If you want to read this book, just google “Larkin Revelation” – there are several websites that contain its text) His ideas refer to the version of this vision in Revelation 11:3-13, but let's not quibble about that.
“The lamp is fuelled by olive oil, which drips from the olive trees into the bowl on the top of the lamp stand. Under the bowl, the lamp stand takes the shape of a menorah.”

So what are the 2 olive trees that fuel the lamp?

It will probably be easier to explain if we go to the version in Revelation 11. 

It starts with the man with the measuring rod - 
Revelation 11: 1 I was given a reed like a measuring rod and was told, "Go and measure the temple of God and the altar, and count the worshipers there. But exclude the outer court; do not measure it, because it has been given to the Gentiles. They will trample on the holy city for 42 months. 
And I will give power to my two witnesses, and they will prophesy for 1,260 days, clothed in sackcloth." 
These are the two olive trees and the two lampstands that stand before the Lord of the earth. 
If anyone tries to harm them, fire comes from their mouths and devours their enemies. This is how anyone who wants to harm them must die. 

These men have power to shut up the sky so that it will not rain during the time they are prophesying; 

and they have power to turn the waters into blood and to strike the earth with every kind of plague as often as they want. 
Now when they have finished their testimony, the beast that comes up from the Abyss will attack them, and overpower and kill them. 

Their bodies will lie in the street of the great city, which is figuratively called Sodom and Egypt, where also their Lord was crucified. 

For three and a half days men from every people, tribe, language and nation will gaze on their bodies and refuse them burial. The inhabitants of the earth will gloat over them and will celebrate by sending each other gifts, because these two prophets had tormented those who live on the earth. 

But after the three and a half days a breath of life from God entered them, and they stood on their feet, and terror struck those who saw them. Then they heard a loud voice from heaven saying to them, "Come up here." And they went up to heaven in a cloud, while their enemies looked on. 
At that very hour there was a severe earthquake and a tenth of the city collapsed. Seven thousand people were killed in the earthquake, and the survivors were terrified and gave glory to the God of heaven. 

Well there’s to lamps burning oil and shining bright - There’s two witnesses attesting to the light
Light atonement’s sorry plight,
Redemption’s joy ignite - Bearing witness, burning oil and shining bright

One of those witnesses is Moses
The one who crossed the Red Sea
He put the hard word on old Pharaoh
Let the people go free

Who’s that yonder dressed in red
Must be the children that Moses led
Passed through the sea those Hebrew slaves
Left Pharaoh’s army to that watery grave

Angel poured his bowl out on the land
Men sprouted sores from their heads to the hands
Angel poured his bowl out on the sea
Lot of creatures died in that catastrophe
For a time, two times and half a time they shine
Grace and truth, the Dark Lord’s evil ways define
Shut the heavens, stop the rain
When their virtue men defame
For a time, two times and half a time they shine

You know that witness Brother Moses
When he crossed the Red Sea
He met with Ja up on Mount Horeb
Brought back the Law for you and me

Who’s that yonder dressed in grey
Never took the chance to learn Jah’s ways
Forty years of wandering most unblessed
Ain’t never gonna make it to Jah’s great rest

Angel poured his bowl on the rivers and the springs
Water turned bitter with a bloody tinge
Angel poured his bowl out on the sun
Scorched the blackened souls of those accursed ones
For half of seven years those lamps do burn
Plague with woes, men who grace and truth do spurn
Call down heaven’s purging fires
When their destruction men conspire
For half of seven years those lamps do burn
The thing you got to know ‘bout Moses
He brought forth water from the stone
First time around he had to strike it
Next time should be Ja’s word alone
Who’s that drinking water from the rock
Made Jah angry at the leader and the flock
Who’s that yonder ate heaven’s bread
Lusting for the food that Egypt fed

Angel poured his bowl on the Beast’s great throne
Lights went out and men did curse and groan
Angel poured his bowl on Eden’s Gate
Evil went forth with words of bitter hate
After three and one half years the dragon roars
From his prison in hell’s abyss he does soar
Those two witnesses assails
Over grace and truth prevails
Leaves their bodies in the street their lights all failed
The other witness he’s Elijah
He shut the heavens stopped the rain
He raised the widow’s son in Sidon
Up from Sheol’s bed of pain
Old Elijah talking to the king
Bring out Baal’s prophets for a final fling
Get ‘em up on Carmel make them jump and shout
Rain fire from heaven in a final route
Angel poured his bowl out in the air
Down in Armageddon they all gathered there
Voice cried out in heaven, “It all is done”
Earth quaked at the arrival of the chosen one
And after three and one half days those lights arise
Those two witnesses ascend into the skies
And the earth does moan and quake
While men in fear do shake
After three and one had days those lights arise

Who’s that yonder dressed in white
Must be the Children of the Israelites
Must be the remnant of the spoil and prey
Emmanuel, God with us, on the Lord’s great day.

Two Witnesses to the Seven Bowls of Judgment