Where is he running?
But it has to be translated correctly. Something like: "Where does he run to?" Or does the one questioning want to know, whether "he" is running on the street or somewhere else?
"Where is he running?" Can that be correct?
Can "Where does he run at?" also be correct?
Not really, because it's considered bad grammar in English to end a sentence with a preposition.
Where does he run? is that incorrect?
Ở, is that like "to" or "at", like the Spanish "en" perhaps?