The main goal that Stalin had for the Soviet Union was to industrialize it. He knew that this was a necessary requirement for a society to become socialist, and thus, eventually communist.
Industrialization refers to the process by which a mostly agrarian and rural society turns into an industrial society (one focused on industry and manufacturing). This usually involves an enormous transformation of the economy.
During the late twenties and early thirties, Stalin pursued an aggressive policy of industrialization in the Soviet Union through the development of ambitious economic policies, including an extensive policy of collectivization.
