For full context if you are searching for the truth read all of chapter 13.
“But in those days, after that tribulation, (Mark verses 13:6-23) the sun will be darkened, and the moon will not give its light; the stars of heaven will fall, and the powers in the heavens will be shaken. Then they will see the Son of Man coming in the clouds with great power and glory. And then He will send his angels, and gather together His elect, (the called, chosen) from the four winds, from the farthest part of earth to the farthest part of heaven.
Parable of the Fig Tree (Mark:12-28
Now learn this parable from the fig tree: When its branch has already become tender, and puts forth leaves, you know that summer is near. So you also, when seeing these things happening know that it is near–at the doors! Assuredly I say to you, this generation will by no means pass away till all these things take place. Heaven and earth will pass away but My words by no means will pass away.
Watch (Mark 13:33-37)
But of that day and hour no one knows, not even the angels in heaven, nor the Son (before his crucifixion he planned as the Son of God, man-made flesh in the world not to foresee) but only the Father. Take heed, watch and pray, for you do not know when the time is. It is like a man going to a far country, who left his house and gave authority to his servants, and to each he gave his work, and commanded the doorkeeper to watch. Watch therefore, for you do not know when the master of the house is coming–in the evening, at midnight, at the crowing of the rooster, or in the morning –lest, coming suddenly, he find you sleeping. And I say to all Watch!”