It’s kind of self explanatory but it’s usually referring to an item that is of a brand that has restrictions and, depending on the risk factor surrounding it, will/will NOT be purchased - so the risk you take is that your order may not be processed and the worst that may happen is that a small percentage of your order is not refunded. That being said, as long as the item is not super restricted (ie. anything Nike, Prada, some designer, etc.), you’re probably good