Yeah, Floating is right.
Experience points are gained when you fill your experience bar (done by collecting experience orbs, by killing mobs, or stealing them from dead players). You can use experience points at an Enchantment table to enchant items with effects, like breaking blocks faster, or being more durable, or extra knockback, or casting fire when struck. After enchanting, the experience points used are deducted from your overall points.
Or for ops, just use /enchant with the enchantment you want.