Polonius arrives in the last moments before his son needs to leave for France and greets him by urging him to leave already, stressing the importance of Laertes' immediate departure.This is then...
a play featuring humor
Hamlet killed Polonius when he asumed Claudius was hidding behind the curtain when it was actually Polonius.
Both times when Polonius hides behind an arras, he does so to eavesdrop on Hamlet.
Polonius is a courtier, and the father of Ophelia (who is Hamlet's 'girlfriend' of sorts).