Acceleration if it is specified as a meters / second then
then acceleration = (a /1000 km) in one sec .
For one hour that is 3600 seconds, it will be ( a / 1000 ) * 3600 kmph
= a * 18 / 5 kmph
In the same way, If acceleration is specified as a kmph, then it will be a * 5 /18 m / sec
Conversion from m/sec to kmph => multiply by 18/5 or 3.6
Conversion from kmph to m/sec => divide by 3.6