Similar to other payment solutions, WhatsApp uses UPI for sending and receiving money.
For almost a year at this point, we've known that WhatsApp has been toying with the idea of adding a peer-to-peer payment service for its users in India. A move like this makes sense for the company, and according to some users of the WhatsApp beta, this functionality is now starting to become available.
Once your account is linked, you'll be able to start sending money to other WhatsApp users by tapping the attachments icon in a conversation. Tapping on a transaction that you send or receive will show its status and which of your bank accounts was used, and after the initial setup process, you can go back to the Payments settings page to view your entire payment history.
WhatsApp uses India's UPI system for managing payments, and supported banks include Axis Bank, State Bank Of India, Yes Bank, ICICI Bank, and plenty more.
Along with being limited to users in India, you'll also need to ensure you're signed up for the WhatsApp beta to start using this. The feature is still rolling out, so if you have trouble linking your bank at first, be sure to try again later on.