This is one of my absolute favorite scenes from Romeo and Juliet! Very simply, Juliet's nurse is joking with Juliet. This is the scene where the audience begins to truly understand the very tender and loving relationship that Juliet has with her nurse. The nurse understands just how much Juliet is looking forward to this news. Further, the nurse already knows the news is good (in other words, that Romeo truly does want to marry Juliet); therefore, she shows her awesome sense of humor by making Juliet wait for it. Even further, the nurse gets joy out of hearing Juliet's reactions:
Juliet. What says he of our marriage? What of that?
Nurse. Lord, how my head aches! What a head have I! / It beats as it would fall in twenty pieces. / My back o' t' other side--ah, my back, my back! / Beshrew your heart for sending me about / To catch my death with jauncing up and down!
Juliet. I' faith, I am sorry that thou art not well. /Sweet, sweet, sweet nurse, tell me, what says my love?
Nurse. Your love says, like an honest gentleman, and a courteous, and a kind, and a handsome, and, I warrant, a virtuous--Where is your mother?
Juliet. Where is my mother? Why, she is within. / Where should she be? How oddly thou repliest! / "Your love says, like an honest gentleman, 'Where is your mother?'"
The nurse's humor continues as the audience enjoys the relationship. I consider this to be comic relief (which is a good thing) for the play is so consumed with suspense for most audience members. In my opinion, the version with Claire Danes and Leonardo Dicaprio is phenomenal during this particuar scene. Both the tenderness between Juliet and her nurse as well as the substantial humor of the scene are unparalleled.