It means, my dear friend,... that our language contains many words having a double meaning; and that to pronounce a joke that allows both meanings of a certain word, proves the joker a person of culture and refinement, who has, moreover, a thorough command of the language.
That proves you are unusual,... and I am convinced that the only people worthy of consideration in this world are the unusual ones. For the common folks are like the leaves of a tree, and live and die unnoticed.
You may have noticed that if one has money without brains, he cannot use it to advantage; but if one has brains without money, they will enable him to live comfortably to the end of his days.