What kind of fire extinguisher can put out a electrical fire?

The extinguisher that has only a green triangle on it would be a really BAD choice because it probably contains water for putting out Class A fires of ordinary combustibles.

An electrical fire (Class C) is signified by the letter C in a blue circle.

Or, you can turn off the electricity and use any extinguisher appropriate for the type of fire that was started by the electricity's heat.