Energy cant be destroyed or crated but it can be converted like you can convert mechanical energy to sound and chemical to light like when you snap a glow in the dark stick.
Different forms of energy can be combined to make an object do something, like when you throw something to something you are using chemical energy of your food to mechanical and elastic of your muscles then gravitational when you throw it up and then when it falls friction is made and that friction makes heat.
Kinetic energy is energy that makes an object move like when you have a chemical reaction that makes a rocket move like bicarbonate-sodium and vinegar pushing a rocket up into the sky.
Potential energy is energy stored in a object like a battery the energy stored can be transformed into other energy.
Why is it important? humans fear the unknown when you know something well you don't fear it you feel confident and have less chance of injury.