“grave / tomb” in Japanese is 墓, read bo, haka (ぼ, はか). It is a Grade 5 Kyōiku kanji, taught in year 5 of Japanese elementary school, and appears in words such as 墓地 (graveyard).
What does 墓 mean?
お墓に花をそなえる。
Same sound, different character — the classic trap. Compare them side by side: