After Benedick exits, young Claudio asks Don Pedro to help him woo Hero. Claudio, apparently, is not a very good lover or speaker. This makes him less interesting to the audience: Shakespeare clearly is using Claudio more as a plot device in order to bring more attention to the real stars of this comedy, namely Benedick and Beatrice.
Don Pedro gladly agrees to help Claudio:
I know we shall have some revelling tonight. I will assume thy part in some disguise,
And tell fair Hero I am Claudio. (268-70)
In order to welcome Don Pedro and his soldiers, the town of Messina is having a big costume party (or masked ball). Don Pedro, therefore, plans to wear a mask and tell Hero that he is Claudio. Don Pedro will woo Hero for the incompetent Claudio, and so help the young lover to accomplish his desire to marry Hero.
The reader here should note that, throughout most of this play, there is an atmosphere of holiday and carnival (a time for fun, amusement, and feasting). The Russian critic Mikhail Bakhtin created the term carnivalesque to refer to this type of atmosphere in a literary work. Humor, craziness, foolishness, and chaos tend to dominate the characters and plot. During this holiday atmosphere, everybody acts irrationally: the regular order and business of the day gets subverted. Everything seems backwards or upside-down. Naturally, such an atmosphere is ideal for a romantic comedy because, when someone is in love, that person becomes irrational and overly emotional. He (or she) becomes a little bit crazy.
The reader should also note that a motif of masking and disguise also appears throughout the play. In this instance, Don Pedro is going to disguise himself as Claudio. Later, Margaret (Hero's servant) pretends to be Hero. Such direct disguises and role- playing should make the wary reader look for indirect disguises -- particularly with Beatrice and Benedick. They disguise themselves as a confirmed bachelorette and bachelor, respectively. Their apparent hatred for one another disguises the fact that they actually are in love with one another.