Lebensraum is a German compound noun. Leben means living, and raum means space, so the word literally means living space, as in the space required for a society to thrive and prosper.
The word Lebensraum was used early in the twentieth century by Germans as part of a plan to colonize other countries, but the word is most strongly associated with Nazi Germany. The Nazis used the idea of Lebensraum, or living space, as the basis of their policy for the expansion of Germany. Lebensraum was the excuse for the invasion of Poland and the desire to occupy Russia. The goal was to use the resources from those countries to benefit Germans and Germany.