When you sell and ship products to customers you need to be ready for returns too. Like it or not but customers do have multiple reasons to return the product to you.
First of all, the customer might not like the product and return it without reason. Second, when the customer does like and use the product, it might be defect and require a replacement or repair service. Third, customers might want to return the product to you when they stop using it.
When customers do return, a lot needs to happen:
The customer needs to inform you about the return
You need to review and accept the return request
You need to define where to send it
You need to create a return record in your system
You need to issue a return shipping label
The customer needs to pack and send the product to you
You need to receive the return shipment
You need to inspect the product
You need to service (e.g. refund) the customer
You need to update the return record in your system
The above is just the happy path. Your returns process needs to be prepared for mass volume and unexpected exceptions. Your RMA software should help you to deal with a customer RMA.