Water stored in dams falls freely with the force to make a turbine move. the turbine moves and produces electricity. this electric energy is supplied to homes. at home, we use electricity for heating, cooling, and lighting.

The water in a reservoir behind a dam is an example of potential energy. The stored energy in the reservoir is converted into kinetic  energy (motion) as the water flows down a large pipe and spins a turbine. Both use a power source to turn the propellers of a machine called a turbine. As the turbine spins, it turns a metal shaft connected an electric generator, which is basically a motor that produces electricity. In the case of a hydroelectric dam, it's flowing water that's used as the power source to turn the turbine.

It is used to during sexual reproduction between humans

The answer is energy. the arrows are showing how exited and energized the stones are.