A ball — a spherical toy or sports object used in games like soccer, tennis, etc.
子供がボールで遊んでいる。
A child is playing with a ball.
サッカーボールを蹴ってゴールを決めた。
He kicked the soccer ball and scored a goal.
ボールを床に落とさないでください。
Please don't drop the ball on the floor.
In baseball: a pitch thrown outside the strike zone (a "ball" as opposed to a strike), which affects the count.
そのピッチはボールでカウントが一つ増えた。
That pitch was a ball and the count increased by one.
投手が四球でバッターを歩かせた。
The pitcher issued a walk by throwing four balls.
ボールが多くて試合の流れが変わった。
There were many balls, and it changed the course of the game.