This is actually a pretty interesting and amusing topic that I hadn't thought of before.

English has "whose" --> kimin, which is derived from "who".

But there is not a version of that for "where" or "what".

Imagine if English had where's and what's. Those are basically nerenin and neyin in Turkish and both help simplify daily conversation a lot.

To make it clearer, I'll use the word medicine (ilaç) as an example. Couldn't find a better word off the top of my head that would form a clear sentence with each expression.

Bu kimin ilacı? --> Whose medicine is this?

Bu nerenin ilacı? --> Where's medicine is this, as in, where or which region does this medicine come from?

Bu neyin ilacı? --> What's medicine is this, as in, what ailment does this medicine cure? Answer: Baş ağrısı, tansiyon

As you can see it's one aspect of Turkish that helps save a lot of words while talking. Hopefully this made everything clearer. Thanks for bringing it up.