Sphere, Ball, Sports Ball
noun
The kanji and the word are exactly the same. That means they share meanings as well. 球 has a slightly technical sound and highlights the sphere shape of the object you're talking about. It's most commonly used to refer to sports balls (as a more formal alternative to ボール).
たま
This word is made up of a single kanji, so it should use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: You see a sphere in Tamara's (たま) hand. You're not totally sure what it is, but it's really spherical. Maybe it's some kind of sports ball. Remember Tamara, the local ball girl? It would totally make sense for Tamara to be holding either a sphere or a sports ball, since that's kind of all she does. You might notice 球 has the same reading as the vocab word 玉. Their meanings are kind of similar too, so this reading should be a bit easier to remember!
ああっ！球がバンカーに入っちゃったよ。
Dammit! I hit the ball into a bunker.
ねぇ、新しい野球の球を買ったんだけど、一緒にキャッチボールしない？
Hey, I bought a new ball for baseball. Do you want to play catch with me?
球の体積を求める公式って何だっけ？
What was the formula for the volume of a sphere?