The "buy one give one free" promotion refers to a promotion where customers can receive multiple items for free when purchasing a certain number (n) of items. Customers can customize and adjust the promotion dates as needed. When the product is set to the "buy one give one free" promotion, the complimentary item's selling price will be zero during POS sales, which will not affect the amount collected but will reduce the inventory quantity.

Click " Retail Backstage " - " Promotion Management " - " Buy One Get One Free " menu, as shown below: