In the cockpit, there isn't room for a car-style brake-pedal, nor for one like the type of a locomotive/parking brake. So the rudder pedal also serve as brakes. They are called 'toe brakes', when the brake is a separate mechanism at the top of the pedal the can be pressed by hence, the toe, without moving the rudder, which would cause movement on the runway/taxiway. On a commercial airline, the rudder pedals also control the nose wheel (same in GA aircraft tail wheel included), but the main steering is done by a wheel that spins like the crank on a bicycle, which is used to move the nose wheel either left or right, whereas the toe brakes are used for added steering since, unlike a car, they can utilize differential brakes.
