Ans
Potential energy is the energy of position. An object at a higher position has more potential energy. The idea is that it has the potential to do work - the "potential energy" can be converted to other kinds of energy. In fact, this could be said about most other kinds of energy as well (that you can convert them to other types of energy). I assume the name is given for historical reasons.
Ans:
Potential energy is the potential to do work. If you lift a block to 20m height, it has the potential to fall through that distance under the force of gravity.
work done = force times distance