How many games are played by one club in a soccer season?

It depends on the league and on how well the team does in knock-out competitions like national cups and tournaments, as well as whether or not the team has qualified for continental level competitions. A team that wins everything can play its 30 league games, 6 or 7 cup games, 11 tournament games and another 11 continental tournament games, totalling 68~9 games.