The watch app works just like you’d expect. When a push notification is sent it will be received by both your iPhone and your Apple watch. Allowing you to accept or decline the push notification from other.

The difference however is with the Apple watch, you’ll notice that there are 3-buttons available, rather than the standard 2 that you see on the iPhone. 

• Approve > Approves the push notification OTP and completes the login.
• Deny > Denies the push notification OTP and prevents the login from proceeding. Requiring you to request a new push notification if login is still required.
• Dismiss > Closes the application, resulting in no action taken. If you select Dismiss, you can still approve or deny the push notification from your iPhone.