if he's a guy with a female body and happy with that, then... non-binary might be a good first label to apply. it's used for any gender identity that isn't strictly male or female. an identity that is male, but with female anatomy is likely to fall under this umbrella, but that's up to your friend to decide really. you may suggest it to him if he doesn't know about it already.
i don't think there's one specific term for your friend's identity, he'll have to read about or talk to people who id as different thingsand maybe he'll end up making his own term for it in the end if none fits exactly.
but that's what i like about non-binary. there are as many different identities as there are people in our group. everybody has a rigjt to choose whay fits them best, make their own label, or not call themselves anything at all other than just another person. most decide on something or other for simplicity, a term that tells they're not exactly the same as everybody else, and kind of in what way.
