The "P" gear position in automatic transmission cars is the parking gear. When a car is parked, the gear position is changed to P, and the wheels are locked in a mechanical state, which can effectively prevent the car from slipping. It is important to note that the car must be completely stopped before using the P gear position, otherwise it may cause damage to the automatic transmission.
While in the P gear position, pressing the brake will not have any significant impact on the car. However, it is important to note that the P gear position should only be used when the car is completely stopped. If you try to accelerate while in the P gear position, the parking gear will be engaged and the wheels will be locked, which can cause serious damage to the transmission and may require replacing the transmission.