What does Lebensraum mean? What did Hitler do to create more “Lebensraum”?

"Lebensraum" translates into "living space." Hitler wanted to create a large German Empire. He hoped to make Germany self-sufficient by invading land occupied by Slavs. Hitler expanded into Poland and the Soviet Union in order to create his "living space." The Slavs who lived there would either be exterminated to make room for the German settlers or be used as slaves. Hitler saw the oil rich lands in Southern Russia as fuel for his war machine and the fertile lands of Ukraine as Germany's future granary. Even during the war Hitler started to offer Germans land in the east with the promise of more lands to come with each inevitable Nazi victory.
"Lebensraum" comes from the idea that the Aryan race was the best in the world and that the Germans were destined to own these new lands. Hitler planned for the German population to grow by giving German mothers awards for having more children. These people would need new places to live, so this became another justification for "Lebensraum." All of this was envisioned with the idea that the Third Reich would last at least a thousand years; fortunately, it ended long before this.