As a buyer, if the product you’d like to buy is listed with free shipping, it’s because the seller would like to offer you free shipping to entice you to buy their product.
As a seller, if your PrestaShop shipping is set to free, it means that you’re absorbing the cost of shipping the product to the buyer. You can change the amount your PrestaShop delivery costs by changing the backend details on shipping, updating the shipping module you are using or by using your Smart Send account to make changes.