Shakespeare is well known for his use of dramatic irony which in most simple terms is when the audience knows something the character does not, therefore the character's actions may lead to irony.
In Macbeth, I'm not sure if you are given specific situations but I think a great example for one is found with Duncan and Macbeth. Duncan greets Macbeth at the castle where he is soon to be murdered, the same place he also describes as 'pleasant'
~I hope this helps!~