The opening line of this novel is quite famous:
It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife.
Such a line begins to establish the narrative voice of the text: it is wry and ironic but often lighthearted and amused as well. This line states, ironically, that everyone knows that every rich bachelor is looking for and in need of a wife. We can tell that the statement is meant ironically because such a belief is certainly not an acknowledged universal truth; rather, it is the belief of a select segment of the population, to those whose main ambition is "to get [their] daughters married [and whose] solace [is] visiting and news." For example, we might expect Mrs. Bennet, a rather ridiculous and silly character, to say something like this, and because she is so obviously ridiculous, we are given to understand that we are not meant to identify or agree with her. The narrator describes her as a "woman of mean understanding, little information, and uncertain temper." Thus, we are not supposed to agree with this opening line, and neither does the narrator (who is much more sympathetic to Elizabeth Bennet's character than she is to Mrs. Bennet).
In fact, shortly after this opening line, Mrs. Bennet actually says to her husband,
A single man of large fortune; four or five thousand a year. What a fine thing for our girls!
She assumes, automatically, that this wealthy bachelor will be interested in marrying one of her daughters. She has no idea what kind of person he is—he could be a horrible person without scruple for all Mrs. Bennet knows—and what matters most to her is that he is single and rich.
This first chapter also introduces readers to the mildly and amusingly antagonistic relationship between Mr. and Mrs. Bennet as well as Mr. Bennet's preference for their daughter Elizabeth. Thus, it does quite a good job of introducing us to the major elements that will continue through the rest of the text.