Revelation 6 tells about the first six of seven seals on the scroll of God which are opened one by one by the Son of God. It starts with the so-called Four Horsemen of the Apocalypse appearing one after another, followed by the beginning of the time of the end and the great day of YHWH.

Revelation 6:1-2 (TS2009) And I saw when the Lamb opened one of the seals, and I heard one of the four living creatures saying, like a sound of thunder, “Come and see.” And I looked and saw a white horse, and he who sat on it holding a bow. And a crown was given to him, and he went out overcoming and to overcome.

The first horseman comes to conquer the earth.

Revelation 6:3-4 (TS2009) And when He opened the second seal, I heard the second living creature saying, “Come and see.” And another horse, fiery red, went out. And it was given to the one who sat on it to take peace from the earth, and that they should slay one another. And a great sword was given to him.

The second horseman comes to bring war to the earth.

Revelation 6:5-6 (TS2009) And when He opened the third seal, I heard the third living creature say, “Come and see.” And I looked and saw a black horse, and he who sat on it holding a pair of scales in his hand. And I heard a voice in the midst of the four living creatures saying, “A measure of wheat for a denarius, and three measures of barley for a denarius. And do not harm the oil and the wine.”

The third horseman brings food shortages and hunger to the earth.

Revelation 6:7-8 (TS2009) And when He opened the fourth seal, I heard the voice of the fourth living creature saying, “Come and see.” And I looked and saw a green horse. And he who sat on it had the name Death, and She’ol followed with him. And authority was given to them over a fourth of the earth, to kill with sword, and with hunger, and with death, and by the beasts of the earth.

The fourth horseman comes to bring death to the earth. These four horsemen will kill a fourth of the earth's population. They make use of the beasts of the earth. This likely implies that they make use of Daniel's Four Beasts that exist shortly before the time of the end. These events will signal the beginning of the time of the end. The prophet Zechariah mentions four chariots, the first with red horses, the second with black horses, the third with white horses, the fourth with speckled horses. The messenger explained: These are four spirits of the heavens, coming forth from presenting themselves before the Master of all the earth. (Zechariah 6:5)

Revelation 6:9-11 (TS2009) And when He opened the fifth seal, I saw under the slaughter-place the beings of those having been slain for the Word of Elohim and for the witness which they held, and they cried with a loud voice, saying, “How long, O Master, set-apart and true, until You judge and avenge our blood on those who dwell on the earth?” And there was given to each one a white robe, and they were told that they should rest a little while longer, until both the number of their fellow servants and their brothers, who would be killed as they were, was completed.

At this time God's chosen ones ask God how long until He will avenge their blood. That the chosen ones in heaven had to wait a little longer until their fellow chosen ones on earth would be killed, confirms that in the time of the end there will still be a remainder of God's chosen ones on earth, and that the government of God's Kingdom is not complete yet.

Revelation 6:12-14 (TS2009) And I looked when He opened the sixth seal and saw a great earthquake came to be. And the sun became black as sackcloth of hair, and the moon became as blood. And the stars of the heaven fell to the earth, as a fig tree drops its unripe figs, being shaken by a strong wind. And heaven departed like a scroll being rolled up, and every mountain and island was moved out of its place.

This is the great day of the wrath of God (Joel 2:31, Acts 2:20). I think it will happen halfway in the time of the end. Peter said that the day of YHWH shall come as a thief in the night, in which the heavens shall pass away with a great noise, and the elements shall melt with intense heat, and the earth and the works that are in it shall be burned up. (2 Peter 3:10) Satan and his demons are thrown out of heaven to earth.

Revelation 6:15-16 (TS2009) And the sovereigns of the earth, and the great ones, and the rich ones, and the commanders, and the mighty, and every slave and every free one, hid themselves in the caves and in the rocks of the mountains, and said to the mountains and rocks, “Fall on us and hide us from the face of Him sitting on the throne and from the wrath of the Lamb, because the great day of His wrath has come, and who is able to stand?”

The ungodly people will flee to their organizations and governments trying to escape God's wrath. Daniel's Four Beasts will merge to form Satan's final global empire as foretold in Revelation 13. Satan's little horn or king will persecute and kill the remainder of God's chosen ones.