What do we learn about the sergeant in Act 1 Scene 2 of Macbeth?

The sergeant appears in a very brief scene to give King Duncan an account of the battle against the traitorous MacDonald, who has been aided by the King of Norway and the Western Isles.

We learn from the sergeant's report that Macbeth has personally slain MacDonald, and that he fought with unparalleled ferocity, like a man "unseam'd from nave to chops." His wounds were so extensive that he looked "like a Gorgon."

The sergeant's description establishes Macbeth as a brave warrior, worthy of the praise he has received.