Pitcher
noun, suffix
You already know that 手 means "hand," but it can also mean "doer," as in someone who performs a particular action or task. Why? Because we use our hands to do things. And when it comes to throwing, the doer is the pitcher!
とうしゅ
This is a jukugo word that uses the on'yomi readings of the kanji. You haven't learned this reading for 手 yet, so here's a mnemonic to help you: To be a good pitcher, all you have to do is put the ball into the chute (しゅ). Pitchers don't actually throw the ball. There is an invisible pitching chute right on the mound. You slide the ball into the chute and off it goes!
父は、プロの投手です。
My father is a professional pitcher.
大谷氏は投手の名人でありバッターの名人でもあります。
Ohtani is a master pitcher and hitter.
メキシコのチームの投手はとても強いです。
The pitcher on the Mexican team is very strong.