If it's a recirculator there will be vents on the front of the unit, and when it is running you will feel air coming out of those.
If it's an extractor there will be a pipe between 3 and 6 inches in diameter (wide) coming out of it. Typically you will see this in the cabinet above the extractor, if you have a cabinet there but sometimes it can go to the side or can be hidden behind a decorative cover. The pipe will go through an outside wall where you will see a small grate or hood. If it's not too high you will feel and maybe hear air coming out of that when the extractor is on. There may be similar grates or hoods on the outside wall for your clothes dryer, bathroom fans, and water heater you need to be sure which one you're looking at. Note, if the extractor is against an outside wall there may be no pipe inside, so the only clues would be the outside vent and the absence of a vent on the front of the unit blowing air when it's on.