What does Matthew 10:7 mean?

This continues a very thorough set of instructions for the Twelve, the hand-picked apostles of Jesus Christ. He is sending them out into Galilee, and only to the people of Israel, for now (Matthew 10:1–6). There, they will do the work they have seen Him doing since each of them began to follow Him.

Now Jesus tells them what they should say to the people of Israel. The message He gives them is the same one proclaimed by John the Baptist (Matthew 3:2), and the lesson Jesus Himself declared (Matthew 4:17). Both John the Baptist and Jesus began that message with the word "repent," and the same is implied here.

In short, the disciples were to go out and tell people that Jesus was the Messiah, the promised King of Israel. His kingdom was near, because He was on the earth now. The time had come for the people to put their faith in the Christ in order to be welcomed into His kingdom. Nobody understood, yet, that the kingdom would begin not with the overthrow of the Romans but with Jesus' death for the sins of humanity and His defeat of death in the resurrection.