Dammit! I hit the ball into a bunker.
What was the formula for the volume of a sphere?
Hey, I got a new baseball. Do you want to play catch with me?
The kanji and the word are exactly the same. That means they share meanings as well. Another meaning I'm going to add is sports ball because this is the word used for balls in various sports (soccer, baseball, etc).
Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word: You're holding onto a sports ball in your hand, let's say it's a baseball for this mnemonic's sake. You throw it at your friend who's going to catch it. As it flies through the air, though, it transforms into a tomahawk (たま). Imagine your shock and fear as you see this happening, flying towards your friend! It's going to stick in his forehead. He can't catch this with his glove!
Also notice that it has the same reading as the vocab word 玉. So, if you know that one, you may know this one too! They're kind of similar.
This can be read きゅう too, if you're talking about more of a globe sphere than the ball sphere you throw.