A natural weapon is a non-manufactured weapon which is part of a creature’s physical form, such as a fist or claw. Such weapons cannot be selected as normal weapon proficiencies; rather, proficiency with them is granted by the feature (typically from your heritage or a feat) that gives you access to the weapon.
Once you acquire a natural weapon, you are always considered to be wielding it unless you equip a different weapon, implement or shield in its place. For example, a claw weapon might be “equipped” in each hand whenever that hand isn’t wielding a different weapon or implement, or using a heavy shield. Most natural weapons are also in the unarmed group, allowing you to continue using your hands for holding or grabbing while you wield them.
Natural weapons can never be removed (stolen, confiscated, etc.) or destroyed. A natural weapon can be enchanted and disenchanted in the same way as any other weapon, except that disenchanting a natural weapon does not destroy it.