The transistor I bought from en electronic market has labeling as “S8050 D 331″. I used a multimeter to measure its hfe value and it shows 186 (varying between 186 and 188).

There are hfe1, hfe2, hfe3 for  this S8050 transistor and for each there are associated MIN, TYP and MAX value. for hfe1and hfe3 there are only a MIN value, but for hfe2 the values MIN, TYP and MAX are all exist. Why is the difference?
What does hfe1, hfe2 and hfe3 mean? If they all exist, do I still have a unique value? Which one of them correspond to the 186 value which I got from the multimeter?
Why for each of them there are a range of values (MIN, TYP, MAX)?  If the hfe has, for example like hfe2, MIN value as low as 100 and MAX as high as 400, then how can I know exactly which hfe value the transistor will operate on, and consequently, how should I design the circuit (resistance values, saturation mode, etc.)?

The forward current gain of a BJT varies depending on the collector current. This manufacturer has provided information on Hfe at three different operating currents that they call 1, 2, and 3.

Manufacturers generally only provide min and max characteristics for parameters that they actually test on each device that they ship. Other information is provided so that the user can get a sense of how the device may behave in various circuits.

The meter you are using probably tests beta or Hfe at a relatively low collector current, perhaps around 1mA. The instructions for the meter may provide this information.