A Return and Refund Policy is a policy that dictates under what conditions customers can return products they've purchased from your ecommerce store and whether you'll reimburse them or not. It will also let your customers know the time frame within which your company can accept returns.
Of course, customers may be unhappy with their order for many reasons. It might arrive damaged, it was the wrong size or it didn't meet all their expectations. They may request a refund or a replacement.