How fast is Mach 2.02 in kilometres per hour?

There is no accurate answer to this because the Mach number involves the speed of sound and this varies depending on the temperature and the height. So, sound travels more slowly as the height increases, which means it's easier to fly at higher Mach numbers at greater altitudes, although you're not actually going any faster.

The answer to your quesion is that the speed of sound at sea level is about 1,236 kph (Mach 1), so Mach 2.02 = 2,497 (roughly, depending on the temprature).