Well, 'buy 2 get 1 free graphic novel' simply implies that for every two graphic novels you buy, the store gives you one at no cost. It's a common marketing strategy used by bookstores or online retailers to encourage customers to buy more. So if you're into graphic novels, it's a great deal as you can expand your collection without spending too much.
This phrase 'buy 2 get 1 free graphic novel' indicates a promotional offer. When a customer decides to buy two graphic novels, the seller will provide an additional graphic novel free of charge. This is beneficial for both the customer, who gets more for their money, and the seller, as it can potentially increase sales volume. Let's say you want to start a collection of a particular series of graphic novels. With this offer, you can get three for the price of two, which is a great way to build up your collection quickly and economically.
It means that when you purchase two graphic novels, you will get one graphic novel for free. For example, if you go to a bookstore and pick out two graphic novels that are part of this deal, at the checkout, you'll be given an extra one without having to pay for it.