Armor Proficiency, Light
Combat
You are skilled at wearing light armor.
Benefit: When you wear a type of armor with which you are proficient, the armor check penalty for that armor applies only to Dexterity- and Strength-based skill checks.
Normal: A character who is wearing armor with which he is not proficient applies its armor check penalty to attack rolls and to all skill checks that involve moving.
Special: All characters except monks, sorcerers, and wizards automatically have Light Armor Proficiency as a bonus feat. They need not select it.
Source: Pathfinder Core Rulebook