Question: How was the Soviet Union affected under Stalin's rule?
One effect was to depopulate it - he murdered millions of citizens in order to control the army and other potential sources of resistance. By the time he had fought WW2 some 25 million Russians had perished - he presided over famine in the Ukraine and did nothing about it. He expanded the USSR into Eastern Europe which precipitated the Cold War - and managed to set in train economic and security policies which would eventually all but bankrupt the country.
That is a big topic. Can you narrow it down? And how long an answer do you want?