In this passage, Friar Lawrence tells the Capulets to not be sad for Juliet even if she has died young. We know that he is saying those words because he knows Juliet is not really dead. He tells them that it is better to be married and die young, than be married for a long time (he is most likely thinking of how Juliet has already married Romeo). Moreover, the friar wants them to take Juliet to church soon because he knows she will wake up and run away with Romeo.
