This quote by Charley in the play Death of a Salesman was said as a response to Linda Loman who, during her husband's funeral, claimed that all that Willy needed was his salary to make ends meet. Charley answers back saying that "No man only needs a little salary" because he has actually experienced the American Dream that Willy does not get to experience.
When analyzed from a closer point of view, Charley has been successful, and has produced a successful child. These were the empty dreams of Willy Loman.
Linda, as a woman in a society that does not understand her, had followed the tenets of her husband and had basically declared that if Willy's company would have just agreed about paying him a salary, he would have been fine.
Yet, Charley comes back to dissipate Willy's fantasies. He represents reality, and not Willy's whimsical dreams. For this reason, he says that money is not the "be all, end all" of life. Charley knows Willy perhaps more than everybody else in the Loman family. The reason behind his words are that he knew, within, that Willy wanted to achieve the same things that Charley achieved. The problem is that Willy never took a second look at himself to really know what he is about. As a result, he led an empty life, with empty children, and no possibilities.
Charley had outgrown Willy, and thus he was able to see beyond Willy's issues. He knew that Willy would have never been satisfied with just "a little salary"; Willy needed security, acceptance, and self esteem. Money cannot buy self-esteem so, perhaps, what Willy needed to finalize his maturity was to understand himself and his limitations. Since he refused to do that, he opted to live a false dream. This false dream is what Charley attempted to destroy but, as the audience finds out, Willy has bought into it too far off and he will never let go of it.