so the 1, 6, 12, 18, 24 are multipliers.
As are the ones in the braces (0.6, 3.8, etc)
The first one is for KM, the second is for miles.
1000 * 1 = 1000 KM
1000 * 0.6 = 600 miles
They are almost the same, its just simple numbers. In actuality, 1000 km is around 621 miles.
So this is saying at 1000km OR 600 miles, you do the first maintenance.
The next one is 6000km OR 3800 miles, and so on.
Hope this helps
EDIT: Stitch beat me to it by a few seconds