What is significance of this Queen Mab's speech at this point of the play in Romeo and Juliet?

The whole speech is based on pagan Celtic mythology. Mercutio’s speech is laced with sexual innuendo. The words “queen” and “mab” refer to whores in Elizabethan England. As the speech goes on, we notice the subtext get increasingly sexual culminating with Mab teaching Maidens how to have sex. On the surface, Mercutio is poking fun at Romeo’s romantic obsessions.