Figures of speech can be recognized as either rhetorical schemes or tropes. Tropes are the most commonly recognized types of figures of speech and refer to things said that have meaning beyond the literal, or an "unexpected twist in the meaning of words" (Dr. Wheeler, "Tropes"). The most commonly known tropes are metaphors and similes. A reader actually won't find many metaphors and similes in Austen's writing as she prefers a more direct style. However, she is certainly quite the wit, and one of the ways in which she is witty is that she creates irony through both exaggerations and understatements. Both exaggerations and understatements are also considered tropes, or figures of speech, and their technical terms are hyperboles and meioses. We certainly see a great deal of hyperboles and meioses all throughout Pride and Prejudice.
We see one example of a hyperbole in the opening line of the book:
It is a truth universally acknowledged, that a single man in possession of a good fortune must be in want of a wife. (Ch. 1)
This is a clear example of exaggeration because, while the women of a village in Austen's time period might have believed this to be true, the men with the large fortunes did not necessarily acknowledge its truth. Since men may not have seen it to be true, it can't really be a "truth universally acknowledged." In reality, a wealthy man may have felt just as inclined to remain single.
One example of meiosis can be seen further down in the first chapter. When Mrs. Bennet is begging her husband to visit Mr. Bingley in order to strike up an acquaintance so that the Bennet daughters can be introduced, Mr. Bennet gives the very sarcastic, understated reply, "I see no occasion for that. You and the girls may go, or you may send them by themselves" (Ch. 1). There are a couple of reasons why this is an understatement. For one thing, Mr. Bennet certainly sees as well as anyone else how important it is to introduce his daughters to men of fortune, especially since the Longbourn estate has been entailed to Mr. Collins and his girls will be left paupers unless they marry well. Hence, Mr. Bennet is being completely sarcastic when he says, "I see no occasion for that," and treating the situation far more lightly than he truly views it. Another reason why Mr. Bennet's dialogue here is an understatement is that he knows perfectly well that it would be entirely improper for a group of women to introduce themselves to a strange man. Hence, suggesting that the girls go alone is certainly making an understatement of a social issue.
Hence, we see that all throughout the book, Austen makes use of both hyperboles and meioses, which are both figures of speech, in order to develop her ironic wit.