What this tile shows
The question behind most discount arguments. Revenue from coupon orders set against what the discounts cost you, so a campaign that looked busy can still be shown to have lost money.
Squizzie calls this one Coupon ROI. It reads as a figure to two places, because rounding it to whole numbers would hide the movement worth seeing.
Where the number comes from
WooCommerce Orders. Order data including revenue, counts, and averages.
What you need for it to appear
Nothing beyond Squizzie and the shop data it already reads.