I'll tell you a secret about time in Swahili. Think opposites on the analog time clock.
Swahili speakers start to count the hours of the day at 6.00 in the morning. As a consequence, saa moja is seven o'clock, saa mbili is eight o'clock, etc. What Dying_Star means: imagine a clock, then one (moja) is exactly opposite (diagonally) to seven.