What does it mean when people refer to Hamlet’s hiring of the players in Act IV as “the play within a play?” What is Hamlet using these players to do?

Select the quote that best shows character. “why should he disturb my peace? ” “excuse me, sir, i am not accustomed to listen to such expressions or to such a tone of voice. i want to hear no more.” “the dear lady may well have taken me for a brigand.” “then you won’t pay me now? eh? ”