what makes the water pump spins

The water pump is bolted to the front of the engine. In the middle it has a shaft coming out of it with a round pulley on the end. A rubber belt is connected to the pulley that turns the shaft, which has a propeller inside the pump to push water into the engine to cool it. The belt is connected to the crankshaft and turns the belt when the engine in running. So the belt turns, and is connected to the water pump, so it "spins". If the shaft spins while the pulley is stationary, the shaft is broken and the water pump needs to be replaced. Normally there are two hoses or three that need to be disconnected and four bolts removed to remove the water pump. Under the radiator are one or two water valves that can be opened to drain the water out of the radiator before removing the water pump.