If someone buys a book, they'll order a copy and have it drop-shipped to the customer, for which you'll get your contracted royalty after it's processed. If no one buys a copy, you won't get a royalty. It's a common practice for booksellers to list books for sale. You could, of course, do what other newbies here have done with this and other companies -- complain vociferously and threaten the bookseller, in which case the bookseller will think your book not worth the trouble and delist the book, eliminating the possibility of a sale. It's not a course of action I would suggest, but, obviously, others feel differently about such things.