Jesus was talking about the Holy Spirit, who would be given to everyone that had faith in him. The Spirit had not yet been given to anyone, since Jesus had not yet been given his full glory.
But the Holy Spirit will come upon you and give you power. Then you will tell everyone about me in Jerusalem, in all Judea, in Samaria, and everywhere in the world."
But they were told that they were serving you and not themselves. They preached to you by the power of the Holy Spirit, who was sent from heaven. And their message was only for you, even though angels would like to know more about it.