A Refund Policy is where you state your policy on whether or not you issue refunds, and in what circumstances this may be limited. You can let users know how to go about requesting a refund, what steps they must take to get one, what form the refund will be issued in, and how long the entire process will take.
A Refund Policy is typically part of a full Return and Refund Policy, or can be the shortened name for the full policy.