The button marked P is the Parking Brake. The other button has an A on it I believe and this is the automatic brake that applies and holds the brake on when you come to a stop and then releases the brake when the gas peddle is pushed to move again. This is handy in heavy traffic or when waiting in line at drive through restaurants etc.. You do not have to keep your foot on the brake after coming to a stop. There is also a setting you can select that automatically applies the Parking Brake when you turn off the car.
Dan
Dan