Merchant payment in Google Pay refers to the ability of merchants to accept payments from customers using the Google Pay for Business app. Merchants can set up their business to accept payments by following in-app prompts to complete each of the required steps, including entering all required details and adding a bank account. Once set up is complete and the merchant can accept customer payments through Google Pay, they will receive a locked scratch card. Benefits of using Google Pay for Business include free, instant payments, enhanced transaction details, and the ability for customers to make payments using a phone number or QR code. The Google Pay Merchant SDK is also available for developers to integrate their applications with Google Pay for accepting payments online.