Power chords are very familiar chords. They’re used in a lot of Rock and Roll music and can be used in acoustic format as well.
They’re formed with two fingers in your left hand.
And look like this on Tablature.
F G A B C D E
These chords are formed with a root note and then another note commonly called the 5th. So you’ll sometimes see these chords written out as A5, or with the number 5. A being the root and the the 3rd finger playing the 5th interval.
Watch this video short on how to make power chords.