Several parts combine into one character.

A textbook indicative character (指事字 / zhǐshìzì): a long horizontal baseline plus a shorter mark above it. The shorter stroke is purely positional — it indicates "above the line" rather than picturing any object. Identical across 繁體 / 新字体 / 简体. Pairs with 下 (below) as the cleanest before/after demonstration of the indicative principle.

Mandarin: shàng, falling 4th tone — the dropping pitch ironically belies the meaning. 上 covers spatial "up", verbal "to go up / get on", temporal "previous", and rank "superior": 上面 (shàngmiàn, on top), 上车 (shàng chē, to board), 上班 (shàng bān, to go to work), 上海 (Shànghǎi, "above the sea"), 上次 (shàng cì, last time), 上课 (shàng kè, to attend class). The verbal use ("get on / go up") is a Mandarin-specific extension that English-speakers must internalize separately from the spatial use.

Japanese: on-reading ジョウ (jō) for Sino-Japanese compounds — 上手 (jōzu, skillful — "upper hand"), 上達 (jōtatsu, improvement), 屋上 (okujō, rooftop), 以上 (ijō, "above and beyond / the above"). Less common ショウ (shō) in 上人 (shōnin, holy person). Kun-readings split into a useful family: うえ (ue, on top of, position) — 机の上 (tsukue no ue, on the desk); あ.げる (a.geru, to raise / give) — 手を上げる (te o ageru, raise your hand); のぼ.る (nobo.ru, to ascend) — 山に登る/上る (yama ni noboru, climb the mountain). The same character drives at least four distinct verbs in Japanese.

Memory aid: a small mark on top of a baseline. The character is a pointer.