You can do it in the head.tpl file of your theme /themes/classic/templates/_partials/head.tpl
or install AdSense module, a bunch of them available https://addons.prestashop.com/en/search?search_query=Google Adsense Ads
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You can do it in head.tpl file of your theme /themes/classic/templates/_partials/head.tpl
or install adsense module, bunch of them available https://addons.prestashop.com/en/search?search_query=Google Adsense Ads