There are different types of energy, such as: kinetic, nuclear, electrical, gravitational potential, elastic potential and chemical.
Energy can be transferred from one object to another and cannot be removed/created. An object above ground has gravitational potential energy and this converts to kinetic energy when it falls.
The conservation of energy is the fact that energy is never lost or gained, and that the same amount of energy is just transferred (even if it to the environment).
For example, a falling object changed gravitational potential energy into kinetic energy…