Several parts combine into one character.

Pictograph: two feet (止) one above the other — left foot then right foot, the alternating motion of walking. The character is itself the verb in motion. Three forms: 繁體 步 / 新字体 歩 (Japan added a small dot to the bottom-right) / 简体 步.

步 covers literal walking, abstract progress, and counting steps as units of distance. As a measure word for steps and stages, it appears in many compounds.

Mandarin: bù, falling 4th tone. 步行 (bùxíng, to go on foot), 散步 (sànbù, take a walk — common verb), 进步 (jìnbù, progress / improvement), 步骤 (bùzhòu, stage / step in a process), 一步一步 (yíbù yíbù, "step by step"), 让步 (ràngbù, to make a concession — "yielding step"), 步行街 (bùxíngjiē, pedestrian street).

Japanese: TWO on-readings. ホ (ho) is dominant — 歩道 (hodō, sidewalk — every Japanese road has a 歩道 sign), 散歩 (sanpo, taking a walk — extremely common everyday word), 徒歩 (toho, on foot — rental ads constantly say 駅から徒歩5分 = "5 minutes on foot from the station"). ブ (bu) appears in 歩合 (buai, percentage / commission). Kun-reading あるく (aruku) is the everyday verb — 歩く (aruku, to walk) is among the highest-frequency Japanese verbs. The variant あゆむ (ayumu, to walk / make progress) is more poetic / formal.

散歩 (sanpo, "leisurely walk") is one of the most useful daily Japanese words — Japanese culture has long valued the contemplative neighborhood walk, and the Tokyo TV show 散歩 has been a national institution for decades.

Memory aid: two footprints — left foot, right foot, the picture of walking.