Reason tells us that a structure that contains the scope of reason can explain. Therefore the fact khan is called Noumena, or things that we understand the reason. (Phenomena)
Reason tells us that the structure with the bounds of reason can be explained only so-called reality, or Kant's Noumena is something we can not understand the reason. Because humans understand the true scope of the world of experience only (Phenomena).
Why tell us as the structure with the bounds of reason can explain only. Therefore, the reality or cant, called Noumena Is what we cannot understand the reason(Phenomena)