The Catechism in Questions & Answers

116. In what way did Jesus Christ fulfil His divine commission?

Jesus Christ acted in the capacity of King, Priest, and Prophet.
When one thinks about a king, one thinks of ruling and governing. In the time of the Old Testament the function of a priest was to mediate reconciliation between mankind and God. A prophet proclaims the divine will and foretells coming events. Jesus Christ performed all of this in perfect fashion.