Several parts combine into one character.

Compound character: 尸 (a reclining body — originally pictographic for "person at rest") + 至 (to arrive). The encoded image: "the place where one arrives and lies down to rest" = home / shelter / building. Identical across 繁體 / 新字体 / 简体.

The character has TWO meaning-tracks across CJK languages: "house / building" (Korean·Mandarin focus) AND "shop / business" (Japanese focus). The Japanese specialization is the most distinctive use.

Mandarin: wū, level 1st tone. 屋 in modern Mandarin typically means "room / house structure" — slightly literary compared to 房 (fáng, building). 屋顶 (wūdǐng, roof), 屋子 (wūzi, room), 房屋 (fángwū, housing / buildings). Mandarin tends to use 房 (room/building) and 家 (home) more than 屋 in everyday speech.

Japanese is where 屋 gains a unique productive use. The kun-reading や (ya) functions as a SHOP-NAME SUFFIX — combine any product with や and you get the shop that sells it: — 八百屋 (yaoya, vegetable store — "eight hundred shop", from variety of produce) — 肉屋 (nikuya, butcher / meat shop) — 魚屋 (sakanaya, fish shop) — 本屋 (hon'ya, bookshop) — 花屋 (hanaya, florist) — パン屋 (pan'ya, bakery — using foreign パン) — 居酒屋 (izakaya, Japanese pub — "stay-drink shop") — 床屋 (tokoya, barber shop) This "X屋" pattern is one of the most useful productive vocabulary tools in Japanese — once you know it, half of Japan's street signage becomes readable.

On-reading オク (oku) for formal compounds — 屋上 (okujō, rooftop), 屋外 (okugai, outdoors), 屋内 (okunai, indoors), 家屋 (kaoku, building / structure).

Memory aid: a person arrives and lies down to rest — the home and the shop where artisans rest between sales.