“heavy / important” in Japanese is 重, read juu, chou, omo (じゅう, ちょう, おも). It is a Grade 3 Kyōiku kanji, taught in year 3 of Japanese elementary school, and appears in words such as 重要 (important).
What does 重 mean?
荷物が重い。
Same sound, different character — the classic trap. Compare them side by side: