The volt is a measure of electric potential. Electrical potential is a type of potential energy, and refers to the energy that could be released if electric current is allowed to flow. (from Wikipedia)
An analogy: If you let a marble roll down a very steep ramp and then let it roll down a very shallow ramp, the marble would have a greater velocity traveling down the steep ramp. A steep ramp has greater potential energy.
An analogy: If you hook up a hose to the outside water faucet and open the faucet valve a little, the water spray goes a small distance. If you open the faucet a lot, the water spray goes a greater distance. Water pressure is equivalent in this example to voltage. The higher the water pressure the higher potential energy.
In electricity, the greater the voltage, the faster the electrons can travel and the more work you can get out of a device hooked to the power source.
A volt meter measures this electrical potential.