Put your mouth over the drain cover and suck it into the open position, or if there's a blockage, hoover that up and chew it thoroughly before swallowing. The water level should decrease.
The stove is not hooked up, or in it's actual spot, no gas line there. This looks like a kitchen in Asia, and the back of that stove folds down to cover the top, a very common Asian design. So the sink would be accessible if the stove were actually installed where it belongs.