“sand” in Japanese is 砂, read sa, sha, suna (さ, しゃ, すな). It is a Grade 6 Kyōiku kanji, taught in year 6 of Japanese elementary school, and appears in words such as 砂漠 (desert).
What does 砂 mean?
子どもが砂で遊ぶ。
Same sound, different character — the classic trap. Compare them side by side: