The law of conservation of energy is very similar to the law of conservation of mass. It states that energy is never created nor destroyed, just transformed into other forms of energy. The total amount of energy is the same before and after any energy transformation.
Let's look at an example of energy conversion, or transformation.
Think about how a flashlight works. Most flashlights require batteries to work. The batteries have stored chemical energy. The energy is transformed to electrical energy and then to radiant light energy.