In cricket, there is a thing called a toss that happens before the start of the game. The toss is like a game where two team captains stand in the middle of the field with a coin. One captain picks heads or tails, and then they flip the coin into the air. The other captain watches to check if the coin lands on heads or tails.
If the captain who picked the side that the coin landed on wins, they get to choose if their team will bat or bowl first. Batting means their team tries to hit the ball thrown by the other team and score points, while bowling means they throw the ball at the other team's players to try to get them "out". If they don't win the toss, the other team gets to choose whether they want to bat or bowl first.
So basically, the toss decides which team gets to choose their strategy first - whether they will bat or bowl first in the game.