To use this simple formula, the 'mass' has to be in kilograms, and the 'speed' has to be in meters-per-second.
You can see that we have a slight problem that has to be cleaned up: The speed in the question is given in "kilometers per hour", but we'll need it in "meters per second". So let's convert that right now:
(600 km/hour) x (1 hour / 3600 seconds) x (1000 meters / km)
= (600 x 1 x 1000 / 3600) (km-hour-meters / hour-second-km)
= 166.67 meters/second .
Now we're ready to plug numbers into the formula for K.E.