The Barracks is the location in wherein you have the option to customize your character by buying skills,Gear, Weapons, and so forth.
The items and skills in the barracks are bought using skill points.
Skill points are earned by going up a level when you reach a certain amount of experience(XP).
As you play the game, you also earn respec points, at a far greater rate than skill points. Respec points are used to completely clear all previous customization choices, and refund all the skill points back to you.