What do you do with your right hand on the piano?
When playing the piano, each hand has a specific function. The right hand, stationed in the treble-clef notes, general plays melodies and the left hand, in the bass quarters, handles the low end. Both hands generally flesh things out by adding harmony.
Why is my left hand so weak piano?
If your left hand is weaker than your right hand, it's possibly because you are right-handed, which would mean your left hand is naturally weaker because you use it less. To counteract this would mean to practice the left hand MORE than the right hand to balance the two hands equally.