What are competitor coupons?

I saw on Alfy's and other places where they say Now accepting competitor coupons. So can you tell me what kind of competitor coupons Alfy's Pizza would accept? And what exactly is competitor coupons.What are competitor coupons?
Competitor coupons are coupons from a business competing with the one in question.

For example. I'd expect that Alfy's Pizza would accept coupons from Pizza Hut, since Pizza Hut would be of their competitors.What are competitor coupons?
ok like you can use dominoes pizza coupons at alfys pretty much. like at grocery stores they have there coupons and they can use other stores coupons at that store also aka competitor coupons