As Pride and Prejudice by Jane Austen is a novel rather than an essay, it doesn't really have a singular abstract meaning. To a great degree, it was intended as entertainment, rather than as a polemic about a specific issue.
The main subject matter of Pride and Prejudice is the hopes and aspirations of young gentlewomen in small towns in the early nineteenth century. For women of this class, their main goal in life was finding a husband, as there were few career opportunities open to women in this period. The main conflict in the plot is between two views of marriage, one which regarded it as a practical economic transaction and the other which hoped for love.
Within the plot, the most dramatic portrayal of this conflict lies in the character of Collins. From a practical and ethical point of view, his offer of marriage to one of the Bennett girls is ultimately suitable, and even admirable. In Elizabeth's rejection of this offer, we see the abstract ideal of a loving marriage in conflict with immediate practicality; in Charlotte Lucas' acceptance of him, we find the older model of marriage as a purely practical arrangement.