“valley” in Japanese is 谷, read koku, tani (こく, たに). It is a Grade 2 Kyōiku kanji, taught in year 2 of Japanese elementary school, and appears in words such as 谷川 (mountain stream).
What does 谷 mean?
谷に小さな川がある。
Same sound, different character — the classic trap. Compare them side by side: