Macbeth and Macduff meet. Macbeth says he has avoided fighting Macduff because he has too much blood on his hands already.
It's unclear if Macbeth is being honest or if he's baiting Macduff.
They fight. Macbeth mocks Macduff, saying his effort is wasted: no one of woman born can beat Macbeth. But Macduff replies that he was "untimely ripped" from his mother's womb" (5.10.16).
The second block of Macbeth's fate slides into place.
Macbeth, suddenly fearful now that the prophecy has turned against him, refuses to fight him. But Macduff calls Macbeth a coward and says that Macbeth will be mocked across Scotland if he surrenders. Despite certain death, Macbeth attacks. Macduff kills him.
Macbeth dies as he lived—a slave to ambition. Lady Macbeth convinced him to sacrifice his honor by questioning his courage, now Macduff gets Macbeth to fight for a lost cause to prove his courage.