Literary realism is a branch of literature which set out to reflect society as it was, to get as close to the bone of real life as it could. It often depicts more humble or banal events than Romantic writers. So most of Jane Austen's novels are realist because they are fairly mundane; they depict fairly ordinary people, usually woman, doing fairly ordinary things. There are few locked room mysteries, no strange and mysterious happenings, or insane wives. The women do ordinary things like get married and the men are fairly ordinary men.
If you compare Pride and Prejudice to a novel like Jane Eyre, the differences become clear: no secret insane wives imprisoned in the home, no misplaced identities and no Byronic heroes.
In a way it could be described as less 'exciting' than Romantic novels but it is a truer reflection of society because it relies less on stylization and more on holding a mirror up to society.
Like the works of some of her contemporaries' novels, Jane Austen's 19th century writings are often referred to as realistic novels. Her books, such as Pride and Prejudice, use fiction to depict as closely as possible the day-to-day experiences of people in a particular time and social class. The characters in realistic novels are complex beings with multifaceted emotions who are faced with plausible, everyday challenges of their era and station in life. Other novelists of the 19th century whose works are classified in the realism category include George Eliot and Leo Tolstoy.