A woman grows up in an inner room, and no one knows what she means. What does this mean?

The neighbor's daughter has just grown up and has been raised in the boudoir. She has never seen her.

There is a girl who just grew up next door. Pregnant in the inner room, no one knows her is an ancient poem, which means: the girl next door has just grown up and has been kept in the boudoir, and people have never seen her. This sentence is usually used to describe a woman who has grown up but has not been known or understood by the outside world.