This is the 2784th most frequent German word.
oberen
"Oberen" means "upper" or "top" (plural or inflected form).
Here, 'obere' modifies 'Regal' (shelf), specifying its spatial position above other shelves.
Das obere Regal enthält alte Bücher.
The top shelf contains old books.
In this sentence, 'oberen' is used as an adjective modifying 'Stockwerke' (floors), indicating their position being upper or located above.
Die oberen Stockwerke bieten eine großartige Aussicht.
The upper floors offer a great view.
'Obere' as an adjective here refers to the relative hierarchical position or importance of the rules.