Several parts combine into one character.

靴 is a phonetic-semantic compound: 革 (leather / treated hide) + 化 (huà, "to transform" — providing the sound). The composite reads as "what leather is transformed into" = footwear, especially boots and crafted shoes. The character pairs neatly with 鞄 (kaban, bag) — both use the leather radical 革, both became everyday Japanese vocabulary, both name the products of hide-craft.

Korean reading "hwa." 軍靴 (gunhwa, military boots), 長靴 (janghwa, "long boot" = rain boots / wellingtons), 運動靴 (undonghwa, "movement-shoe" = sneakers / athletic shoes — universal Korean term for sneakers), 登山靴 (deungsanhwa, mountaineering boots), 防寒靴 (banghan-hwa, winter boots). Almost all Korean Sino-Korean compounds for shoe types use 靴, while everyday "shoes" remains the native (sinbal).

Mandarin xuē, 1st tone. 靴 (xuē), 靴子 (xuēzi, boots — colloquial), 雨靴 (yǔxuē, rain boots), 马靴 (mǎxuē, "horse-boot" = riding boots), 长靴 (chángxuē, long boots / knee-highs). Mandarin reserves 靴 specifically for boot-style footwear; everyday "shoes" is 鞋 (xié) — 鞋子 (xiézi). The split is clean: 鞋 = generic shoes, 靴 = boots.

Japanese on-reading カ (ka) is barely used. Kun-reading くつ (kutsu) dominates — and dominates everyday Japanese vocabulary: 靴 (kutsu, shoes — the everyday word), 靴下 (kutsushita, "shoe-under" = socks — perfectly logical), 靴ひも (kutsuhimo, shoelaces), 運動靴 (undōgutsu, sneakers — using kun-reading kutsu with rendaku to gutsu), 革靴 (kawagutsu, leather shoes). Unlike the Korean / Chinese narrowing of 靴 to just boots, Japanese 靴 covers ALL footwear — sneakers, dress shoes, sandals, boots all called kutsu. The same word, different scope across languages.

Memory aid: leather (革) transformed (化) — what hide becomes through craft = footwear.