He is one of Earth's Mightiest Heroes. He uses magic to protect us from a bunch of threats we don't really ever find out about and aliens who invade our planet sometimes and try to murder us. Or I guess half of us is more accurate.

[Kamala exhales audibly. That's a long and sad story she rather not get into.] One of our heroes called him "Sorcerer Supreme" which I guess means he's the most powerful magic user we have.