Free Will suggests that as humanbeings, we are selfdetermining and free to choose our thoughts and actions.
What does having a belief in free will not deny
Having a belief in free will does not deny that there may be biological and environmental factors that exert influence on our behaviour which are outside of our control but implies we are able to reject these forces and behave as we choose.
What does having the belief in free will mean isn't possible
Having this belief means that it isn't possible to preciselypredict human behaviour