Complex sentence: Overall, Juventus is the club that has contributed the most players to the Italian national team in its history, they are the only Italian club that has contributed players to every Italian national teams since the 2nd FIFA World Cup.
Split into simpler sentences: Overall, Juventus is the club that has contributed the most players to the Italian national team in its history. They are the only Italian club that has contributed players to every Italian national teams since the 2nd FIFA World Cup.