Wordpress allows you to add shortcodes in your functions.php file. Shortcodes a bits of code you add to your content box and WordPress will run a piece of code in this spot.
A previous example of shortcode is the snippet of Creating a WordPress shortcode to view PDFs.
Google adsense is a advertisement service which will display adverts on your website and when your visitors click on an advert you earn some money.
Below is a snippet you can add to your functions.php to create a shortcode to add Google adsense to your page.
Now in your content you can add the shortcode.
This will add the Google adsense to your content where you add the snippet.