It means that he cares about you as a person, but he is not interested in you romantically. He is not interested in dating you, but hanging out together would be OK, but just as friends. Unless you have feelings for him, in which case you should not be hanging out with him because you would just get hurt.
It depends on how long youve known him, how he says it, weather you get jealous when hes with another woman and vise versa. It usually means your a good friend.