I believe he means a literal bin. E.g. Amazon takes products from all their sellers and chucks them in the same physical space, so they have no idea who actually sold the product when it's picked. So you could have gotten something from a dodgy 3rd party seller that repackages broken returns, etc, and Amazon doesn't maintain oversight of this.

Literally just a bin in a fulfillment warehouse.

An amazon listing doesn't guarantee a particular SKU.

Ah, whew. That's what I thought. Thanks! I asked because we make warehouse and retail management systems and every vendor or customer seems to give every word their own meanings (e.g., we use "bin" in our discounts engine to be a collection of products eligible for discounts, and "barcode" has at least three meanings depending on to whom you're speaking).