wheel bearing problem

My son has a 98 Ford explore 4x4 and he says his front left bearing is bad
had to drive it home and said wheel is tilted in don't know how much but
its not drivable now. so my ? is how much of a job is it to replace one.is
it just a bearing or the whole hub. I havent seen it yet but Im most likely
gonna do it cause he's not that good at working on stuff like this. price
for a new one about 170 some bucks (OUCH) or is the bearing capable of
being pulled from hub and replaced ????