What does the boy mean when he says that two people's constellations are very compatible?

He is flirting with you. There are only two kinds of men: one is purely thinking about picking up girls, that is, he loves to impress you with words and actions, but he doesn't really want to be with you, just wants one more person to like him, and he has a great sense of accomplishment. The other is that I am really interested in you and want to go further with you. You can get a general understanding from his circle of friends, friends around him and his usual speaking style, and realize that if people think he is sincere, then take good care of it and come on!