Mat 25:13 Watch therefore, for you know neither the day nor the hour wherein the Son of man comes.
Alternative: Wake up because you cannot see the day or the hour in which the son of man is on his way.

This connect the previous parable about the virgins to the story in the previous chapter (Mat 24:42) where Christ says that we do not know when we will be taken or left. Again, it is the hidden nature of God and our deaths that makes our choices throughout our lives as important. It doesn't matter where we start. The worst mistakes can always be redeemed. It only matter where we end. The problem is that we do not know when the end comes.

The idea is that we must work every day to make the most of what we have. This, of course, leads us directly into the next parable in which the virtue of making money is taught.

"Watch" is from grêgoreô (gregoreuo), which means "to be or to become fully awake."

"Comes" is from erchomai, which means "to come" and "to go." It means "to set out" and "to arrive at." It is a little like we use the phrase "he is on his way,"or "to be under way," which can mean either that he is coming or going with no direct reference to the position of the speaker.