The one and most important outcome of the nonaggression pact between the Germans and the Soviets before the start of the World War II was that the Germans managed to act freely in Eastern Europe.
By managing a nonaggression pact with Stalin, Hitler played well tactically in order to be free to attack the Eastern European countries and expand the German territory. Stalin was very thrusting of Hitler, so he was sure that Hitler will just lead the Germans up to the Soviet Union border and stop there.
Germany managed to occupy one by one pretty much all of the countries between them and the Soviet Union without any opposition by another strong nation, in this case the Soviets. That though kicked back on Stalin and the Soviets because Hitler decided to attack them once he reached the border, which was very shocking and unexpected by Stalin, as he trusted Hitler and thought that he will not betray him, especially not in that manner.
