The phrase "to fight back" means to resist or oppose something with force, determination and courage. It implies taking action against an opponent, a situation or circumstances that are unfavorable or harmful. To fight back can mean physically defending oneself or others from attack, standing up for one's rights or beliefs in the face of opposition, or working to overcome obstacles and challenges. The phrase is often used metaphorically to describe a person's attitude or approach towards difficult situations, indicating their willingness to take action and not give up easily.