Some users do suggest that people take a look at a similar feature implemented by Facebook on its Messenger platform to get an idea on how the entire system will work. (This makes sense, given that the social media giant also owns WhatsApp)
On Messenger, those who have Facebook accounts may send money to other accounts on the social networking site. Before the transfer takes place, the application asks the users to enter necessary details like credit card or debit card information. Once these numbers are registered, people may now start sending money to their friends or contacts.
Hopefully, WhatsApp’s implementation also retains the near instantaneous money transfer that Messenger’s implementation has been known for. In the latter, money is directly debited from the person’s checking account and then brought over to the bank account of the receiver. Direct money transfer reduces the time needed to complete transactions, especially when compared to other solutions that may still involve the use of digital wallet services like Paypal. It will likely take several weeks or even months before the feature is deployed on the stable version of the application. Even so, the payment transfer service will probably be limited to a select set of countries.
More details on this Beta Version will likely be released soon.