A storage space or storeroom — a place to put away items in a house or building, including sheds or small storage rooms.
物置に古い家具をしまっている。
I have stored old furniture in the shed/storage room.
物置の鍵をなくして、中に入れない。
I lost the key to the storage room, so I can't get inside.
冬用のタイヤは物置に保管しておいてください。
Please keep the winter tires in the storage room.