The concept "free will" is regarding the idea of having a degree of control over one's actions and choices, without complete restrictions. The term is often linked to religious beliefs, particularly in the context of a deity with omniscience, omnipotence, and omnibenevolence, who could be seen as responsible for harm that occurs in the world.
However, the notion of free will only requires the ability to conceive of more than one potential action, even in situations where one may be physically restricted. Even strapped to a chair, you could preconceive a variety of actions to take. This capacity is inherent to a functioning brain, unless it is severely damaged. The term "free will" serves as a way to reconcile the cognitive dissonance caused by the idea of an all-knowing and all-loving deity who doesn't prevent harm.
The concept of a being with omniscience raises the question of why such a being would allow harm to occur, despite having the ability to predict and prevent it. Religious apologists have attempted to avoid this conflict with the idea of "free will" - the belief that humans have the capacity to make independent choices that are not predetermined. However, it's possible for a being with omniscience to limit the harm caused by/to humans without negating their free will.