This is the 12133rd most frequent German word.
uno
"Uno" is not a German word; it is Italian and Spanish for "one."
Here 'Uno' is used as the name of a specific card game, which is a noun.
„Uno“ ist ein populäres Kartenspiel.
"Uno" is a popular card game.
In this sentence, 'Uno' refers to the game being played.
Ich habe beim Spiel Uno gewonnen.
I won while playing Uno.
Here 'Uno' is referenced as a proper noun and is described as the popular game.