Here's a translation: The car goes in a constant velocity in a straight line as the movement of the pendulum is described by the observer. So the movement of the pendulum should be backwards because the pendulum is not the car but it is moving just as fast, but you still have vectors of gravity pulling it downwards.
Basically, the car is moving forward but the pendulum, at an angle (likely 45 degrees depending on the speed of the car) is tilted backwards.
