What does Luke 21:27 mean?

Jesus gets to the good news after multiple warnings about terrible future events. The disciples believe that Jesus' triumphal entry is just a preview of what is soon to come. They believe He is their Messiah, and that their Messiah is a military and political leader who will gather the Jews, oust Rome, and reestablish the nation of Israel.

Everything that has happened recently confirms their anticipation. Jesus has just debated the Jewish religious and civil leaders about who has authority. His bold claims and understanding of Scripture left the leaders silent (Luke 20). Jesus and the disciples left Jerusalem and climbed the Mount of Olives. Looking west, they can see the beauty of the temple (Mark 13:1).

Jesus jars them from their reverie, warning that the temple will be destroyed. When they ask what signs will mark that time, He gives them a list of hardships they must endure: false teachers, earthquakes, betrayal by friends and family, and the destruction of not just the temple but all of Jerusalem (Luke 21:6–24). God's judgment will reach the whole earth. The sun, moon, and stars will darken and fall. The seas will turn to blood. Satan and the demons will find the power over the world they have always sought (Luke 21:25–26). But then, the Son of Man will return. "The Son of Man" is a title Jesus often used. He is fully God, but He is also fully man. Here, Jesus directly references Daniel 7:13–14:

"I saw in the night visions,
and behold, with the clouds of heaven
there came one like a son of man,
and he came to the Ancient of Days
and was presented before him.
And to him was given dominion
and glory and a kingdom,
that all peoples, nations, and languages
should serve him;
his dominion is an everlasting dominion,
which shall not pass away,
and his kingdom one
that shall not be destroyed."