There is a unit called KWH which is distinct from KW. You kinda rolled right past that in your question. The H is for hour.
KWH is KW, for an hour. It is kilowatts x hours. (It is not kilowatts / hour).
Let's say you have a heater kicking out ~3000BTU or 1000 joules/sec. That heater is drawing 1.0KW.
If you ran that heater for 1 hour, it would use 1.0 KWH.
If you ran it for 5 hours, that'd be 5.0 KWH.
So if you have a unit that draws 168 kwh/annum, kilowatt and hour are on the top of that fraction, and year is on the bottom.
Note that year and hour are both units of time, and can be made to cancel out. We can multiply anything by 1.00 and it will stay the same, so we can multiply it by any fraction where above and below the line is the same thing: 1/1, 44/44, 1k/1000, or 24hours/1day.
- 168 kWh/year x 1 x 1 = 168 kWh/year x 1 year/365 day x 1 day/ 24 hour.
- Units can cancel too. "year" is on top and bottom, gone. 168 kWh x 1/365 day x 1 day/24hr.
- Do the same canceling with "day". Giving 168 kWh/365/24 hour.
- Hour also cancels out, so we have 168kw/365/24.
- Remove the kilo: 168000w/365/24.
That is the number of watts the appliance burns on average. I don't have my calculator, you can do the math.
Or straight to your question: 168kwh/yr x 1yr/12month = 168kwh / 12mo = 14 kwh/mo.