Van is on Turkish time, UTC+3, like the rest of the country. What changes from city to city is the daylight.
Turkey keeps one time zone across roughly 1,600 km, so the clock in Van matches Istanbul exactly while the sun rises at a different moment. The figures above are calculated for Van's own coordinates and update as the date changes.
Van sits on the eastern shore of Lake Van, Turkey's largest lake, close to the Iranian border. It is the furthest east of the cities on this site and therefore the clearest illustration of what a single national time zone does.
The sun rises over Van roughly an hour before it rises over Istanbul, even though both cities read the same time on the clock. In practice that makes Van's winter afternoons end very early.
Van is in the Eastern Anatolia region of Turkey.