@Ace2213 we have a Support Guide about this here:
tl;dr - A deployed website at Netlify cannot run PHP code. Client side javascript can call APIs which are powered by PHP, but the web server itself isn’t running PHP.
To summarize, you can run PHP (or a number of other languages) during the site build process at Netlify. Netlify does not support running an application server (aka: language runtime) during site browsing - only during the build process.
This is because Netlify is specifically designed for JAMStack sites:
With a Jamstack site, there is no code executed on the server - so all dynamic site content must come from javascript in the end user’s browser making API calls.
If you have other questions, we are happy to answer.