The ball of the the car tow bar is pushing on the trailer coupling. The rear point of the car is behind the front point of the trailer.
The rear point of the car is pushing on the front point of the trailer.
In terms of language the car is 'pulling' the trailer as the trailer is essentially behind the car.
In terms of mechanics, though, the car is pushing the trailer. There is no 'pull' at all.
Mechanically the situation is no different to the entire trailer being in front of the car.
If you grab your desk and try and move it towards your self, you will probably language the situation as trying to 'pull' the desk towards your self. Mechanically though you will find your grab and exertion is a series of pushes. There will be some desk in front of your hand with respect of the direction you are trying to move the desk.
The point was everyone says gravity is a 'pull' but no-one can explain the mechanics of a 'pull'.