Hyperbole is a figure of speech that is an obvious exaggeration created for effect or emphasis.
An exaggerated character herself, the Nurse enters the scene in Act III with yards of clothing catching the wind, prompting Mercutio to call out, "A sail, a sail!" Previously in Act I, Scene 3, she employs hyperbole for emphasis to Juliet. As Juliet's mother suggests a husband to her daughter in the form of the young nobleman Paris, the Nurse attempts to underscore Paris's attractiveness by expressing her glowing praise for him:
A man, young lady! Lady, such a man
As all the world--Why, he's a man of wax. 1.3.77-78
With these words, the Nurse tries to convince Juliet that Paris is as great as any man in the world. Moreover, he is as perfect as a wax model; it is as though he were sculpted and given perfect features and perfect proportions. Then, after Lady Capulet comments that no summer in Verona is as handsome, the Nurse adds, "He's a flower, in faith, a flower!" (1.3.80)
By this expression she means that Paris is as handsome as the summer to which Lady Capulet alludes in the previous line ("Verona's summer hath not such a flower").