Potential energy is a way that we see and detect energy.
When you first start learning about energy, it means anything that's moving has kinetic energy. In electricity and magnetism, matter has electric and magnetic fields which use energy to push and pull in their interactions. In thermodynamics, energy is expressed by the motion of moving particles, which we refer to as temperature, which is most often expressed as entropy (because entropy is fascinating - other scientific fields use Helmholtz free energy or Gibbs Free energy, but they're closely related).
Energy is an important property of nature because it is conserved. We can go very far when we find things in nature that are equal. If you shoot one pool ball into another and you want to know where the targeted ball will go. In order to answer this, you need to know what is the same before and after the interaction. It's interesting--not much is the same after the interaction. The direction the initial ball was going does not need to be the same, the speed the ball was going does not need to be the same, but we find that the total energy of the two pool balls is the same over time. This is a quantity that is conserved over time, and we call it energy. Because it is conserved over time, we can predict the future.
The way I informally see potential energy is energy that is not interacting with anything but could. If potential energy does interact with something, we call the interaction a different name than potential energy, such as kinetic energy or force.