When you're barefoot, you're not wearing any shoes or socks. It might feel good to walk barefoot on a sandy beach on a warm day, but just don't try entering a restaurant barefoot.
Some kids might spend the whole summer barefoot, walking down sidewalks with their sneakers in their hands, and if you're a lifeguard or a professional gymnast, you get to be barefoot at work. The Old English root of barefoot is bærfot, combining bær, "naked" or "uncovered," with fot, "foot."