To activate YouTube TV and enter the activation code, follow these steps:

1. Launch YouTube TV App: Turn on your smart TV or streaming device and navigate to the tv.youtube tv/start enter code app.

2. Sign In with Google Account: If prompted, sign in to your Google account. Use the same account that you used to subscribe to YouTube TV or that you want to link to your YouTube TV service.

3. Navigate to Activation Screen: Once signed in, you may see a screen asking you to activate your device. Look for an option that says something like "Enter Code" or "Activate".

4. Visit Activation Site: On a computer or mobile device, open a web browser and go to tv youtube com/start.

5. Enter Activation Code: On the activation page, you will see a field where you can enter the activation code displayed on your TV screen. Type the code exactly as shown on your TV.

6. Activate Device: After entering the code, click on the "Next" or "Activate" button on the website. This will initiate the activation process.

7. Confirmation: Wait for a moment as the tv.youtube tv/start activate code. You should see a confirmation message on your TV screen indicating that your device has been successfully linked to your YouTube TV account.

8. Start Watching: Return to your TV and navigate through the YouTube TV app. You should now have access to live TV channels, DVR recordings, and on-demand content based on your subscription.

9. Troubleshooting: If you encounter any issues during activation, double-check the entered code for accuracy, ensure your TV and device are connected to the internet, and visit the YouTube TV Help Center for further assistance.

By following these steps, you should be able to activate YouTube TV on your device using the activation code provided and start enjoying its content seamlessly.