“flat / level” in Japanese is 平, read hei, byou, tai (へい, びょう, たい, ひら). It is a Grade 3 Kyōiku kanji, taught in year 3 of Japanese elementary school, and appears in words such as 平和 (peace).
What does 平 mean?
平らな道を歩く。
Same sound, different character — the classic trap. Compare them side by side: