What is a furlong?
A furlong is 220 yards or 660 feet, which is exactly 201.168 meters. It is an eighth of a mile.
The origin of the term "furlong" can be traced back to Old English, where "furh" meant "furrow" and "lang" meant "long." This reflects the historical use of furlongs in measuring the length of a furrow in agricultural fields. In horse racing, furlongs are used to measure the distance between the starting point and the finish line. A racecourse typically consists of multiple furlongs, with the most common distances being 5 furlongs (5/8 of a mile) and 8 furlongs (1 mile).
Outside the racecourse the furlong has almost gone. British racing still gives distances in miles and furlongs, so a mile and a quarter is written 1m 2f. Road signs don't use it – they give miles and, for short distances, yards.
What is a kilometer?
A kilometer is 1,000 meters, or about 0.621 miles. 'Kilo' is the Greek-derived prefix for a thousand. It is the unit for road distances nearly everywhere except the US and UK, which still use miles.
A kilometer is about 3,281 feet or 39,370 inches. At a walking pace of 5km/h it takes about 12 minutes to cover.
Going from kilometers to meters just means moving the decimal point three places. A mile has to be broken into 1,760 yards or 5,280 feet first, and neither of those is a round number of anything.