Your webstore subdomain is the unique address for your storefront. While the main domain for all webstore users is webstoreplace.com, each user has a unique subdomain which by default is the seller’s eBay user ID.
A subdomain is a separate site, even though it doesn't have it’s own domain it can have an unlimited number of pages.
If you wish to have a seprate domain for your storefront and don’t want to have only a unique subdomain, your can forward a diffrent domain to your webstoreplace.com subdomain. To do so read our guide on How to Register & Forward A Domain for Your eBay Storefront.
If you have any question in regards to your webstore subdomain feel free to comment here below.