A foot is to a human what a hoof is to a horse, a goat, or a giraffe. Each hoof protects the animal and helps it to walk and run.
A hoof is made of keratin, just like your fingernails, but it tends to be thicker and harder since it has to bear the weight of the animal. Hoof can also be a verb that, surprisingly enough, applies to humans. Maybe you have offered someone a ride, only to be told, "No, I think I'll just hoof it," meaning walk or otherwise go on foot. Hoof is sometimes substituted for dance if the person doing it is getting paid.