It's been years since I read this, but from what I recall, it represents society's expectations/treatment of women.
Her obsession with the wallpaper grows as her husband refuses to let her write, see anyone, or go anywhere else. She starts to destroy the wallpaper because she doesn't know how to destroy the social constructs.
I think I remember her continually trying to find a pattern but saying that there was none, that it was just ugly and non-sensical. I think this is commentary on why women were treated as second class citizens - was there any good reason? Any pattern that suggested it made sense? No.
She eventually finds that at night, when any sort of light shines on the wall (enlightenment/being able to see it for it what it is separate from everything else surrounding it) it looks like bars. This suggests that when you actually shine a light on the wallpaper (focus solely on society's expectations of women) you can see it for what it is: a prison.
By the end of the story it drives her quite mad and she becomes the woman in the wallpaper. She wants so badly to get out but she can't recognize that the wallpaper symbolizes something in her own life. At the end she says something incredibly insightful and so on point but you know she doesn't realize why it's so true and it's heartbreaking - something about her husband being in her way of escape and having to creep over him every time she wants out.
Great story. :)