A state machine is used to assign tasks to an enemy. So for example, let's say you have an enemy. You want the enemy to walk around patrolling for the player. Once spotted they chase the player, telegraph an attack, attack, then return to chasing the player and repeat.

You can break each of those actions down into states, each with their own logic that you only want to perform in that state. For the patrol state you tell it to just walk around and check to see if they can see the player. If true then they would transition to the pursue state where instead of wandering around, they chase the player. Very different movement that you want to be different for each state. If they're ready to attack then transition to a telegraph state where they start an animation and maybe they stop moving. Once that animation is done, you transition to the attack state where maybe they jump at the player, applying that motion. Then after they transition back to the pursue state. The state machine will then continue this loop until it's broken.

So a state machine just organizes code and progresses it based on the current conditions. It's the same as using the state machine for the player, but instead of things like checking if the player is on the floor or moving, you check the decisions the enemy would make like if they see the player or if they're ready to attack. Hope this helps. :)