This is similar to the gravitational potential, except it is for electrical charges. Electric field is a vector, i.e. it has both magnitude and direction. The unit is volt . One volt is one joule per coulomb. A conductor allows electrons to pass with little loss of energy.
Examples are metals, such as copper.
An insulator does not allow electron to pass through. Examples are plastics. The unit is ampere, which is coulomb per second. Electric current can be produced by a chemical reaction, such as in a battery or with a mechanical generator. When a battery is connected to a bulb, the bulb provides the resistance, while the battery provides the potential.