This is the text that displays in the discount code entry field before your customer types into it. This is generally used to let your customer know what this text field is for.
Upcart is not able to support all discount functionality available in checkout.
Multiple discount codes are not supported.
Multiple automatic discounts can be used at a time, but there can only be one manual discount code. Customers must go to checkout to apply multiple manual discount codes.
Free shipping discounts are not supported.
Customers must go to checkout to apply free shipping discounts.
Shopify Plus stores using checkout.liquid are not supported.
Shopify Plus stores using checkout extensibility are supported. The discount codes module will be hidden on the real storefront if your store is using checkout.liquid.
Please make sure to review if these are applicable to your store.