"What does he wish from her?"
Translation:¿Qué desea él de ella?
I think if you wanted to include "él" it would need to be right after the verb "¿Qué desea él de ella?". I'm not sure if it can go at the end of the sentence.
I also don't think you can include the "a". It can't be a "personal a" since those are only for direct objects ("he" is the subject), and there's no other reason I can think of to include it.
Someone may need to correct me here but I believe your spanish - Qué desea él de yo - would most directly as: what does he wish from I/me?. I would hazard a guess that the spanish you are looking for from your english would be: Qué desea él para mi (maybe with a personal "a" in there somewhere. From and for being two different things in both spanish and english
Desea is a verb. Verbs agree with their subject by person, count and formality, not by gender. You're thinking of adjectives which agree by gender and count, and tend to end in 'o' or 'a' (eg alto(s), alta(s) meaning tall).
Deseo could be a verb meaning "I wish/desire" or a noun referring to a desire or a wish.