Simple Definition:

A volt is a unit of measurement that represents the amount of electrical force or pressure [the push or pull that makes electric charges move] in a circuit. It measures how much potential energy [stored energy that can be used in the future] is present to move electrons and create electric current [the flow of electric charges].

For example, when you plug in a lamp and turn it on, the voltage determines how bright the light shines. If the voltage is too low, the light may be dim, but if the voltage is too high, the light might flicker or burn out.

Very Simple Definition:

A volt is a way to measure how strong electricity is. It tells us how powerful the electricity is in a circuit.

For example, when you use a battery to power a light, the more volts the battery has, the brighter the light will shine.