Answer:
the action the motor does to a boat is to propell it.
the boat engine propells the boat acroos the sea, river or lake.
I think what the questioner wants to know is whether the propeller pulls or pushes.
You are right, the propeller pulls the boat through the water in the same way a propellor on a 'plane pulls itself though air.
Yes, but it can be debatable whether it pushes or pulls. If the propeller is at the stern of the boat one can argue it is pushing, If it is forward of the middle of the boat (which is rare) one can say it pulls. What a propeller really does is move through the water similar to the way a screw moves through wood. This develops thrust which moves the boat forward. Propellers are usually at or near the stern, and sometimes behind the stern because there the water is less disturbed. It is more efficient.