What does the quote "Suit the action to the word" from Shakespeare's "Hamlet" mean?

In Act 3 Scene 2 Hamlet is discussing with the actors how he wants them to play their parts in his trap for the King.  He tells them first not to over act but then he says for them “Be not too tame neither, but let your own discretion be your tutor: suit the action to the word, the word to the action; with this special observance, that you o'erstep not the modesty of nature:” 

Hamlet is trying to encourage the actors to think about what they are saying and act accordingly.  Don’t over act, but don’t forget their words and don’t underact.