How Do You Put Typed-Up Python Code Into a Functioning App?

I’m looking up how to create my own mobile app (when I should be doing school, job-search, etc.).

But I can’t find the step that explains:

How you turn all that typed up code…
Into a functioning, visual, clickable app?

My brain can’t comprehend how words become apps.

Cuz code is all typed out in words.

Please no make-your-own-app sites (unless they’re more flexible than I think). I want an app that works exactly the way I want it to.

An answer would be very much appreciated.

P.S. it doesn’t have to be python. Just that I plan to learn Python for BGE, and it’d be cool if I can easily transfer the skills to mobile-app making as well.

But it would be awesome if I can make apps for both Firefox phone OS and Android.

Thanks!