In Path of Exile 2, abilities and skills come from Skill Gems which can be slotted into a new menu separate from your Armor. To unlock Skills in PoE 2, you will get Uncut Skill Gems (and Uncut Support Gems) from monster and chest drops, as well as some quests. After using an Uncut Skill Gem, and selecting a Skill to unlock, you will be given a Skill Gem of the chosen ability in your inventory.