Physical gift cards are printed cards that resellers display in store for customers to pick up and bring to the till. Each card carries the product's brand, a 19-digit card number and a barcode.
A printed card has no PIN and no value. It becomes a gift card only when one of your tills activates it, for the amount the customer pays. Activation issues a new PIN to the customer by email and the card number stops working, so cards on display are worth nothing to a thief.