Number
Count, Amount
The kanji and the word are exactly the same. That means they share meanings as well.
かず
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:
Imagine yourself counting by playing a kazoo (かず). Each number you count, you toot your kazoo. How fun!
おかしいわ、どうしても数が合わないのよ。
Oh weird, the numbers don't match for some reason.
1985年におきたニューヨーク大地しんの死しゃの数は何人でしたか？
What was the death toll of the 1985 New York earthquake?
この映画には、数々の日本映画のお兄ちゃん役で知られているコウイチが、数を数えるのが得意な数学教師の役で出演しています。
In this movie, the role of the math teacher who is good at counting is played by Koichi, who is known for playing the role of numerous older brother figures in countless Japanese films.