What does Mark 11:2 mean?

On the sixth day before the Passover, Jesus and the disciples had reached Bethany on the eastern slope of the Mount of Olives where they ate with Mary, Martha, and Lazarus (John 12:1). When the Jewish religious leaders hear Jesus is with Lazarus again, they resolve to kill them both (John 12:9–11). This is the next day.

We don't know exactly where Jesus and the disciples spend the night, other than on the Mount of Olives (Luke 21:37). Many people had travelled from Galilee to Jerusalem for the Passover, so the Mount may have been crowded. There are only two significant towns in the area: Bethany and Bethphage. Since Jesus and the disciples stop in Bethany (John 12:1), and He and the disciples must travel through Bethphage to get to Jerusalem, it may be that Jesus sends the disciples to Bethphage to get the colt. Matthew 21:2 mentions that Jesus tells the two to find a donkey with a colt, and to bring them both. We don't know how old the colt is; the fact that it has never been ridden before and it is still with its mother indicates it is quite young. The fact that the colt is also tied shows he is at least old enough to wander from his mother.

The fact that the colt has not yet been ridden connects to the idea of sacrifice. In that era, only "unused" animals were used for such sacrifices. Jesus will be riding on an animal which is symbolically "untouched."

Along with Zechariah 9:9, in which God tells Israel "your king is coming to you…humble and mounted on a donkey, on a colt, the foal of a donkey," this incident may also relate to Genesis 49:10–11. As Jacob is dying, he blesses Judah saying his descendants will forever rule the nation and he will tie his donkey's colt to a vine. This has led some scholars to posit that the foal and his mother are tied to a vine at the village gates.