In order for this report to be useful, you will need to have input the cost price data into your items. In the below screenshot, we see what happens when this is not the case - all the costs are 0, which means that we cannot use this report.
Therefore, if you think that you will have use of this report, it is important to input the cost price of your items.
Note that there are two entries for refunds. These are Total Refunds, and Refund Wastage.
Whenever you refund an item, you will be asked if you want to return that item into your inventory. If you select yes, then that refund will be displayed under Total Refunds. If you select no, it will go under Refund Wastage.