Essentially, the Goal is what the Protagonist pursues or tries to accomplish in the story.  It is the item or situation or result they will work towards and take steps to obtain or achieve, especially throughout Acts 2 and 3 of the story or storyline.

In The Martian, Mark Watney’s goal is to survive on Mars long enough to be rescued. In The Revenant, Hugh Glass’s goal is to kill John Fitzgerald. In Spy, Susan Cooper’s goal is to stop a terrorist attack.

Near the end of the story in the battle or climax, the Protagonist fights the Opponent for the goal.  This scene is vital in storytelling, because this is the moment when you answer the question you’ve posed to the audience for the entire story: “Will they do it?” 

In their respective climactic scenes, Mark Watney makes a last-ditch effort against the harsh Martian environment (and space) to reunite with his crew. Hugh Glass duels John Fitzgerald. And Susan Cooper confronts the nuclear terrorist in a helicopter chase.

In some projects the goal shifts at different parts of the story.  Sometimes this is because new information has been revealed, sometimes it’s because the character has gone through personal growth that has affected their way of looking at the world, and consequently, their priorities.  When goals shift in a story they usually change from a material goal to a moral goal.  

In There’s Something About Mary Ted pursues Mary using disingenuous methods so he can be with her, but then works to make her happy, though it means giving her up. 

In Room, Brie Larson’s character Ma first seeks to escape the room and then struggles to adapt to normal life.

In Avatar, Jake starts out trying to earn the trust of the Na’vi so that he can betray them but then finishes the story fighting to protect them because it’s the right thing to do.