What does Matthew 23:11 mean?

This repeats something Jesus has said several times to His disciples: that greatness in the eyes of God is different from greatness in the eyes of men (Matthew 19:30; 20:16). In fact, the most godly role to which one can aspire is to be a servant to others (John 13:12–16). This perspective is given in a clear context, and a clear contrast. Jesus has just forbidden His disciples from taking titles for the sake of worldly honor, as the scribes and Pharisees were doing.

Not long before this, Jesus explained this same concept in detail. This was in response to arguments between the disciples about which would take the greatest positions in His kingdom:

"You know that the rulers of the Gentiles lord it over them, and their great ones exercise authority over them. It shall not be so among you. But whoever would be great among you must be your servant, and whoever would be first among you must be your slave, even as the Son of Man came not to be served but to serve, and to give his life as a ransom for many." (Matthew 20:25–28)