Energy is the ability to do work.
Kinetic energy is the energy that is energy possessed by a body by virtue of its motion.
$$ K = \frac12mv^2 $$
Where K is kinetic energy, m is mass and v is velocity.
Kinetic energy is represented using $K$, $KE$, or $Ek$
Potential energy is the energy that is possessed by the body by virtue of the position.
An example of potential energy is gravitational potential energy. This is the energy held by a body due to its relative position to other bodies.
For gravitational potential energy, the below formula applies.
$$ U_g = mgh $$
$U_g$ is gravitational potential energy, m is mass, g is gravity and h is height.
Energy can neither be created nor destroyed in an isolated system.
However energy will be transferred. For example, if you drop a ball from a building the potential energy will decrease, but the kinetic energy will increase.
The work done by the sum of all forces acting on a single body, is equal to the change in kinetic energy.
The net work done on a system is equal to the change in kinetic energy.