Spot-fixing is a way of cheating when betting- you can bet on events in a game, like when the bowler makes a mistake, so if you pay the bowler to make a mistake at a certain time, you can bet on this and win. In the cricket tour, it is alleged that bowlers were deliberately making mistakes at certain points in the game. It caused a huge scandal and undermined people's faith in the integrity of the game, which iis what rocked the sport means.
Guys can be male and female nowadays; in the past, the word tended to refer to males only. It's a countable noun, so use -s for more than one.
Student or Learner