In one's good books

He is not in her *books*

Could anyone tell me what that means?

Thanks

Maybe: not in her good books? Not in favor with her.

Merriam-Webster online: in one's good books : in favor with one

It is also used as in one's black books which, quite obviously, means the opposite of what ESC has suggested.

Actually if you are in someone's 'little black book,' I believe you are most definitely if favour with that person.