A direct competitor to other digital payment apps like Venmo and Square Cash, Apple Pay Cash was announced in June at Apple's annual developers' conference. In the case of the Apple Watch, that requirement is watchOS 4.2.
Funds received through Apple Pay Cash can be transferred back to the bank. However, as of now, the feature is restricted to the United States and later on the feature will be made available in the other markets as well.
The latest smartphone OS data from Kantar Worldpanel ComTech https://www.kantarworldpanel.com/global/News/Later-iPhone-X-Release-Hurts-Apple-Share reveals that "in the three months ending October 2017, iOS share fell in key markets, making clear the impact of the flagship iPhone X not being available to buy in the month of October". They can also use it as payment in stores which accept Apple Pay.
Apple customers who don't already have Apple Pay set up on their supported device can still receive money from friends and family without needing to install a new app or add a card to Wallet. The latest version of iOS comes with some important security updates, it also adds in new features like Apple Pay Cash in the US. Before proceeding with the update, make sure that your Apple Watch is on its charger and is at least 50 percent charged. After this, users will need to launch the Watch app on their iPhone and head to the My Watch tab and then General Software Update.
As of now, the Apple does not offer Apple Pay support in India, however, the company officials are in talks with the PayTm to launch the Apple Pay within Q1 of 2018. Since there's no keypad, you'll have to ask Siri to pay someone using your money.