A kilometer is composed of 1000 meters. The term "kilo" means "a thousand."
So 5 kilometers means 5 1000 meters, thus it is equal to 5,000 meters.
1 km = 1000 meters
5 km * 1000 m / km = 5 * 1000 m = 5,000 meters
1 m = 0.001 km
5 km * 1m/0.001km = 5 m / 0.001 = 5,000 meters