Whilst verifying your site with Adsense, they may ask you to add some code to the <head> section of your site.
How to verify your site
1. Copy the verification code from Adsense.
2. Go to your WordPress dashboard.
3. Go to the pipdig > Theme Hooks page.
4. Paste the code into the “Code to add to the <head>” box, as shown below:
Click the save button at the bottom of the page and this code will be added to your site. You can now verify your site with Adsense.
For more information on setting up Adsense with WordPress, you may find this guide from WPBeginner useful.