I understand if you don’t quite understand how someone is not male nor female or is both. Or identifies in said way. But what I do not understand and what I will not tolerate is you as a human being not gendering them as they ask you.
If a stranger gets all offended that you misgendered them, then they’re being dramatic.
But if a friend, someone you know and love or care for tells you, “I would like to be referred to as they instead of he, now.” Then just call them they! Who cares if you don’t understand a single thing about non-binary.
It’s their life, it’s how they feel, and they are proud enough and they care enough to share it with you. It isn’t actually any of your business but they care enough to inform you on who they feel they are. They can explain their gender IF YOU WANT, but don’t get annoyed or frustrated if they explain exactly what you asked them to. And if you’d rather not know the specifics, then don’t ask.
Just go with they or them. Black and white are hues that can mix with any color. It can’t be just black or white. It never is.