This feature is designed to incentivise customers to review purchased products, as this can create on-site content to strengthen a store's SEO. It automatically emails customers following a successful order, offering them a discount voucher redeemable against future purchases in exchange for an on-site review of their recent purchase. When a customer writes a review, it's stored within the admin system for consideration, and if/when published, the feature automatically emails a single-use discount code to the customer. Etailers can edit the value of the master discount code voucher via their store's admin system.
Please note that this feature is only available to stores with a Product Reviews module.