What does Revelation 8:6-13 mean?

Now the seven angels who had the seven trumpets prepared to blow them. The first angel blew his trumpet, and there followed hail and fire, mixed with blood, and these were thrown upon the earth. And a third of the earth was burned up, and a third of the trees were burned up, and all green grass was burned up. The second angel blew his trumpet, and something like a great mountain, burning with fire, was thrown into the sea, and a third of the sea became blood. A third of the living creatures in the sea died, and a third of the ships were destroyed. The third angel blew his trumpet, and a great star fell from heaven, blazing like a torch, and it fell on a third of the rivers and on the springs of water. The name of the star is Wormwood. A third of the waters became wormwood, and many people died from the water, because it had been made bitter. The fourth angel blew his trumpet, and a third of the sun was struck, and a third of the moon, and a third of the stars, so that a third of their light might be darkened, and a third of the day might be kept from shining, and likewise a third of the night. Then I looked, and I heard an eagle crying with a loud voice as it flew directly overhead, “Woe, woe, woe to those who dwell on the earth, at the blasts of the other trumpets that the three angels are about to blow!”

English Standard Version (ESV)