hub = the metal thing your rotors mount on to, and the thing that has the wheel studs stucking out of.
wheel bearing = inside the hub.
screaching noise = bearing rubbing hub.
take wheel off.
spin the hub by hand, and see how smoothly it turns, and listen for scratching noises.
mine wouldn't make any noise at first, but when i get to my destination i could hear it.
so if i drove it and did the test, i'd fail, but if just got up jacked the car up and did the test, i'd pass.