It means "struggle".
This sentence comes from "Struggle to Encourage Oneself" written by Mao Zedong in 1917. The original text is: Struggle with God, the joy is endless! Struggle with the earth, the joy is endless! There is endless joy in fighting with others!
This struggle to encourage oneself actually reveals two important contents of the development of human society: productivity and production relations. Struggle with heaven and earth is "productive force"; struggle with people is "production relationship".