I have been interested in coding stuff for making sound or modifying sound of a given file for a while. Never have done any coding for sound tools. Any pointers, where I could start? Hopefully not too math heavy?

Think you're gonna have to be a bit more specific what kind of sounds you want to make, or how you'd like to modify them. The space is very wide in general, when it comes to "generating sound". Also, a lot of sound generator/modification will involve quite a bit of math, but with the right environment, you can make it more around trying different things and seeing what sounds good, rather than writing algorithms with text.

A very easy way to get started would be to use something like NoiseCraft, here is one example of what you could do: https://noisecraft.app/608

Then if you'd like to create more advanced stuff (or rather, faster at creating more advanced stuff, NoiseCraft can do a lot in the right hands), Max for Live is a pretty solid environment: https://www.ableton.com/en/live/max-for-live/

I would like to be able to output sound files like some *.wav or so directly from a programming language, writing code, which works with frequences, amplitude, channels, creating effects like ramp off or other things one can see in tools like audacity.

This is probably more mathematical than using existing tools. I definitely want to touch the code, and I would like to have an understanding, so that I could do it in almost any programming language.

Perhaps there is something beginner friendly, that also explains the math behind it for non mathematic / physics degree owners? Maybe I should look for something like "sound processing/generation from scratch".

It's using SuperCollider under the hood (https://supercollider.github.io/) which describes itself as "A platform for audio synthesis and algorithmic composition"

You can pretty much achieve anything in terms of programmable music composition with Overtone/SuperCollider.