You are misunderstanding the confusion, Kwh is an absolute measurement of an amount of power, not a rate of power usage. It's like being asked how fast your car can go and answering it can go 500 miles. 500 miles per hour? Per day? Per tank? It doesn't make sense as an answer.
Does your computer use 100 watt hours per hour? Translating to an average of 100 watts power usage? Or 100 watt hours per day maybe meaning an average power use of about 4 watts? One of those is certainly more likely but both are possible depending on your application and load.
He might, but he also might mean that he has a power meter that is displaying Kwh since last reset and he plugged it in and then checked it again later when it was all set up after an arbitrary time period and it was either showing the lowest non-zero value it was capable of displaying or was showing a number from several hours.