In what situation does the 'o' sound like well... an 'o' and when does it sound like an 'a'. This is in the Russian language by the way. I know it has something to do with being stressed, but can anyone answer it REALLY simply please?

Some Russian letters change their behavior depending on whether they’re in a stressed or an unstressed syllable. The vowels a, o, ye, and ya do this a lot. When stressed, they behave normally and are pronounced in the usual way, but when they’re in an unstressed position, they go through a process called reduction. This deviation in the vowels’ behavior is a very important linguistic phenomenon that deserves your special attention. Not knowing it is like a double-edged sword: not only does it take other people longer to understand you (they simply won’t recognize the words you’re saying), but you also may find it hard to recognize the words you think you already know (but unfortunately store in your own memory with the wrong stress).

Explanation:

Link:

https://www.dummies.com/languages/russian/sounding-like-a-real-russian-with-proper-pronunciation/

I hope this helps^^

sorry if I'm wrong