How to adjust refrigerator temperature/power?
There is no standard, and you cannot know what the numbers mean, at least without the user manual. If it is important for you to keep a certain temperature, get a fridge thermometer and use that. Be certain to measure in multiple places, or in the place you are most interested in because the temperature varies throughout the refrigerator body. 

A second way would be to try to jump through hoops with customer support (maybe send them a photo of the refrigerator? or turn it around and see if you have a model label and/or serial number somewhere around the compressor) and have them locate a user manual for you, or maybe even the temperature itself. But this will only give you the temperature the designers intended, which is not exactly the same as the actual temperature in the fridge.