It's a rather old-fashioned term, so it's not used as often these days.
Here's a breakdown:
* La: The feminine singular definite article ("the")
* Bonne: This can mean "good" or "maid." In this context, it refers to a female domestic servant.
So, "la bonne" literally translates to "the good woman," but in a more modern context, it's understood to mean "the maid."