Why was Operation Barbarossa such a catastrophe for the Nazis?

August 1939, Europe slid towards another world war, Germany And the Soviet Union Came to signed a non-aggression treaty given the ideological differences between the two countries, Hitler to ignore western diplomatic moves and invade Poland. Well I'm Not So Sure About This Question Too, I'm Trying.

Operation Barbarossa (German: Unternehmen Barbarossa) was the code name for the Axis invasion of the Soviet Union, which started on Sunday, 22 June 1941, during World War II. The operation put into action Nazi Germany's ideological goal of conquering the western Soviet Union so as to repopulate it with Germans.