選手

In a sentence

• 彼は野球の選手です。

  He is a baseball player.

  Here, '選手' is used to refer to someone who plays a sport, specifically a baseball player.

• サッカー選手になりたい。

  I want to become a soccer player.

  In this sentence, '選手' is used to express an aspiration to become an athlete in soccer.

• オリンピックに参加する選手たちは一生懸命練習します。

  The athletes participating in the Olympics practice diligently.

  '選手たち' is the plural form and refers to the group of athletes participating in the Olympic Games.