It's a common phrase used to refer to:
* Pieces in a lower level of a house or building: This could be a basement, a ground floor, or even just a lower level compared to where the speaker is.
* Pieces that are physically lower than others: This could be used to describe things like furniture, decorations, or even artwork placed on a lower shelf or level.
The exact meaning of "pieces en bas" will depend on the context of the conversation.
For example:
* "Où sont les pièces en bas?" - "Where are the pieces downstairs?" (Referring to rooms or spaces)
* "Je vais mettre les pièces en bas du placard" - "I'm going to put the pieces at the bottom of the cupboard" (Referring to objects)
If you can provide more context, I can give you a more accurate and specific translation.