The formula with 1.2 substituted
miles = 1.2 ÷ 1.609344 = 0.746
The constant is an exact definition, not a rounded factor: the mile is 1.609344 km, the US gallon is 3.785411784 litres and the imperial gallon is 4.54609 litres. The Kilometres to Miles Converter explains where each comes from and gives a longer table.
At a walking pace of 5 km/h, 1.2 km takes about 14 minutes. At an easy running pace of 10 km/h it takes about 7. In metres it is 1,200.
What 1.2 kilometres means in practice
Around 1.2 km is the walk many city planners treat as the outer limit people will comfortably cover to reach a bus stop or railway station. It is three quarters of a mile, near enough, and about 14 minutes on foot.