Hello piyush262.
Thank you for using Apple Support Communities. It looks like you're experiencing issues attempting to set up your cellular plan on your Apple Watch. If so, we'd like to look into this issue with you.
In the screenshot you shared, we see that you're getting prompted to set up your plan. What happens when you select "Set Up Mobile Data"? Does it not respond? If so, you can try restarting your Apple Watch to see if that helps:
How to restart your Apple Watch
If that doesn't work, you'll want to review the following resource below:
Set up cellular on Apple Watch
Be sure to review all the steps listed under "Before you start".
Feel free to keep us updated. Kind regards.