踏む
ふむ · fumu · JLPT N4 · verb-godan
to step on
👣 fumu sounds like foot-move: move your foot down onto something
踏 has the foot radical 足 on the left, so the kanji itself says foot. Pair that with the sound: fu-mu ≈ foot-move. A foot that moves down onto something is stepping on it, which is exactly what 踏む means.
踏 — foot radical 足 + 沓 (phonetic)
踏 combines the foot radical 足, which signals meaning related to feet or walking, with 沓 as the phonetic component hinting at the sound. The character originally meant to step on or tread, and this core sense of placing the foot down has remained stable through history.