accessory; attachment; appendage
Refers to something that is attached to or belongs to a main object, such as accessories, attachments, or appurtenances.
This vacuum cleaner comes with many attachments.
I attached the drawings as an appendix to the contract.
付属品 is more common for accessories or parts that come with a product, while 付属物 can also refer to abstract attachments or appendages.
Standard kanji spelling.
Variant spelling using 附 instead of 付; both are used, but 付属物 is more common in modern Japanese.
Compound of 付属 (attachment, belonging) + 物 (thing).