How do I display a page in only one language in a multilingual site?

Hello,
i use 9 different languages on my website. Now, in order to make the site appear in only one language, I need to save it in the other 8 languages and set it to: publishing - false.This is very time consuming and not very user-friendly. Is there a way to disable the display of pages in other languages by default? For example, if I save a page in English only, so that it doesn't appear in German? (Error 404 displayed)

Thank you very much for your help and apologize for my bad English.
Daniel

copy and paste the same page.en.md etc like page.es.md on the same folder

Hello,
thank you for the answer but is there a solution for a user who does not have access to the source files?

I got it to work by setting pages_fallback_only: true