Electric Power consumed by the bulb is indicated in Watts (W).
Note: Power in "Watts" = voltage in "volts" * current in "amps", is know as Ohm's Law.
For example, in North-America, residential electrical circuit are normally 120 volts and 15 amps. Therefore, electric power is 120 V * 15 A = 1800 Watts. Light ouput will depend on electrical power but also on the bulb system and the light source (incandescent, halogen, fluorescent, LED etc).