Your nose is the body part sticking out of your face (not that pimple, the pointy feature with two nostrils used for smelling).
A nose is a sense organ — your nose tells you if the milk's gone bad or the cantaloupe is ripe. Dogs' noses give them even more information, about where their owners have been or which neighbor cats have been hanging out in their yards. If someone says you "have a nose" for something, they mean you're talented at it. As a verb, nose means to pry or meddle, or for an animal to push its nose against or into something.