This sentence is a famous saying of Lei Feng.

The sentence "Invest your limited life in unlimited service to the people" expresses Lei Feng's attitude and pursuit of life, that is, he is willing to use his life to help and serve the people and realize himself value of life. Specifically, "limited life" means that human life is limited and everyone has only one life, while "infinite service to the people" means that serving the people is endless and requires continuous dedication and effort. .

Therefore, the meaning of this sentence is to require people to cherish their lives, integrate personal value and significance into serving the people, and strive for life to realize the cause of communism.