I was studying prepositions and stumble upon this phrase "(1) go for a walk (2) go to a walk" which one from these two is correct and why?
If the walk is a destination/event (such as a walk to end cancer, a school walk-a-thon, etc.), you could use "go to a walk" or "go to the walk."
However, in most circumstances, "walk" does not represent a destination/event, and you should say "go for a walk."
This web page might help you out further (Collins Dictionary) by giving you some example sentences.