The Law of Conservation states:

Energy cannot be created nor destroyed but it can be transformed from kind to another; the total energy in the universe is constant
A bowling ball is rolling down a hill, what energy is being lost and what energy is being gained.

As the bowling ball accelarates down the hill, potential energy is lost and is transformed into kinetic energy.
What is eletrical energy?

Eletrical energy is the movement of electrons.
What is energy measured in?

Joules (J)