Like Barbatos, the Goetia says Buer ‘ appeareth in Sagittary.’ It also says “that is his shape when the Sun is there,” but it isn’t really clear what ‘that’ refers to. It might mean he appears as a Great President, or it might mean he appears as Sagittarius. If he appears as Sagittarius, then he looks like a centaur. If he appears as a Great President, then maybe he looks like Lincoln or Washington.
He’s a bit of a teacher, dabbling in Philosophy (moral and natural), and the art of logic. He knows the powers of all plants and herbs, their healing/destructive properties, I suppose. He can cure all illness and he’ll summon up a good Familiar spirit for you if you want.