"Long time no see" means: I have not seen you for a long time.
It is a grammatically comical greeting with English words organized by Chinese grammar. In Chinese there is an everyday greeting "Hao jiu mei jian" which corresponds with "long time no see", literally word by word. It is said that "Long time no see" was first used by Chinese-Americans.
Long time no see! Cuban ex-President Fidel Castro makes a rare photographed appearance.