Minions are creatures under your direct control, usually by magical means, taking your commands on your turn.
Minions are different than followers. Followers act on their own, and are usually controlled by the GM, or maybe a player.
You have a pool of AP, known as Minion AP, that is used to command minions. When a minion acts under your command, it drains your Minion AP. Unless modified by a feature or a Keystone, you start your turns with 6 Minion AP.
A minion cannot use more AP than its maximum amount of AP that it would have if it were not a minion, and just a creature. For example, if you were to magically control a humanoid character as a minion, they would be able to use a maximum of 6 AP on your turn. A Lesser Skeleton would be able to use a maximum of 3 AP on your turn, due to it having a maximum AP of 3.
You cannot spend your Minion AP on commands if you are Incapacitated.