Hi @Simba_Mfalme. Thanks for being part of GoDaddy Community! Unfortunately, the ability to add Google AdSense code is only available for US accounts currently. If you're not in the US, then that's probably why you're not seeing the option. Sorry
On the Top LEFT beside the GODaddy Logo there is an icon which is a globe, click on that. Choose your Country/Region
Click on United States English
Then Log in.
Then go to Edit Sites
Then you'll find on the left side panel: Display Ads, Paste the script there, then publish