Energy is the ability to do work
Work is using force to move mass over distances.
So think about it. A really easy example of using energy is moving a heavy box. Work is using your muscles (force) to move the box (weight). And it requires energy to do that. The more work, the more energy required.
Energy can come in different forms, but mainly exists in two types:
Stored energy (potential)
Working energy (kinetic)
Hopefully, the other forms of energy sound pretty familiar to you. See the picture below:
Energy is measured in joules
A joule is the amount of energy needed to apply a force of 1 Newton for 1 meter. See the picture below.
This law states that energy can neither be created nor destroyed.
Rather, it can only be transformed from one form to another.
For example, when you clap your hands, you are using energy form your body to move your hands, transforming some of that kinetic energy into sound energy and thermal (heat) energy.
Move on to "Potential and Kinetic Energy"