Voltage is a measure of electrical energy. If you've got a high-voltage personality, people may use another electrical metaphor and describe you as "a live wire."
Someone calculates voltage by determining the difference in electrical charge between two points in a circuit. When you travel, you'll want to make sure you bring along adapters to plug into the various sorts of electrical outlets you'll encounter around the world. Your chargers and all your electrical gear should have dual voltage capability, so they can work on electrical currents of 100 volts to 240 volts.