You are equally adept at using either hand.
Without this feat, a character who uses their off hand suffers a -4 penalty to attack rolls, ability checks, and skill checks.
You ignore all penalties for using your off hand. You are neither left or right handed.
This feat helps offset the penalty for fighting with two weapons.
A ranger wearing light armor or no armor can fight with two weapons as if he had the feats Ambidexterity and Two-weapon Fighting.