Open Circuit Voltage
Open circuit voltage is the voltage at the electrode before striking an arc (with no current being drawn). The open-circuit voltage is much like the higher surge of pressure you might observe when a water hose nozzle is first opened.

It is easy to see that the initial pressure from the garden hose was higher than the pressure of the continuous flow of water. The open-circuit voltage is usually between 50 and 80 V. The higher the open-circuit voltage, the easier it is to strike an arc because of the initial higher voltage pressure.

Additional question?

What is Close Circuit Voltage? –> See: Typical Welding operating Voltage