Elizabeth's character is unconventional, that is, she is ahead of her times, of independent thinking, high self-esteem and uninhibited by society, as opposed to all the other women surrounding her.
She is a young woman with wit and beauty (though not as beautiful, apparently, as her sister Jane) who is "at age" to become engaged and married, but would not do so unless she feels comfortable and happy. This was a notion completely unacceptable in her day, and would have put her in a position to become a dependant spinster- her mother's biggest nightmare.
However, as the story develops we see why she is that way: She is a great sister to Jane, and a loving person with set ideals on what love and life should be like. She tolerates with dignity and charm those limits society puts on women, but she candidly dodges or avoids them through intelligence, and avoidance of major drama. She is open and bold enough to talk to a man without blushing, and of giving her opinion of things, even when not asked. She seems to have an intellect that is superior to everyone else's, and her wit can take down the likes of Lady Katherine, her mother, her father, Darcy, Wickham, and even her sister Jane.
She declared that she was not the best musician, nor the best reader, but she definitely shines at doing her minimum all because Lizzie is way ahead of the game in all sorts. In not so many words, Lizzie is the baseline of the modern society woman.