Canada's national sport is ice-hockey in the winter, and lacrosse in the summer. In a game of Lacrosse, players have to pass a ball using a stick with a net, and score points.
(Le sport national du Canada est le hockey sur glace en hiver, et la crosse en été. Pendant un match de crosse, les joueurs doivent se passer une balle en utilisant une crosse munie d'un filet au bout et marquer des points.)
The difference between the active and passive voice is whether the subject of the sentence (in this example the dog) is performing the action, for example: “The dog catches the ball”, this is the active voice, because the dog is the one catching the ball.
Now for the passive voice: “The ball is caught by the dog”, here the focus switches away from the dog and onto the ball, making it the passive voice.