As a self publisher there are many things you’ll need to set up to be a publisher.
The first is a thirteen digit number known as the International Standard Book Number (ISBN). The ISBN represents the worldwide identification system that was started in the 1960s and pubilcations are tagged with this number identifying the connection between publisher, title, author and edition. ISBNs can be purchased as one or in blocks of numbers, 10, 100 etc. There is a special font that is created to make the 13 digit number into what is called a barcode. This barcode is then placed on the bottom right of the back cover design. The barcode is scanable for inventory purposes. If you make your book into an paperback, hardcover, ebook,, and audio book, you’ll need to assign a new ISBN number for each separate ‘edition’. Check with the ISBN organization for all publication information.
The type of barcode assigned to printed book is called EAN. I suggest waiting to purchase your barcode until it is assigned to a specific project when you know what the price will be, eliminating the possibility of having to label your books if the price is missing.
Resource links for any of the services above and many more for the self publishing industry, can be found at https://www.bookcoverdesigner.com/author-resources.html