Several parts combine into one character.

Pictograph: a foot (止 element on top) emerging from a cave or pit-dwelling (凵 element below). Oracle bone forms show the foot stepping out of the curved enclosure — the moment of leaving. The character has stylized over millennia but the encoded meaning ("to exit / step out") never moved. Identical across 繁體 / 新字体 / 简体. Pairs with 入 (enter) as the cleanest in/out opposition.

Mandarin: chū, level 1st tone. 出 covers exit, departure, production, and emergence: 出去 (chūqù, go out), 出来 (chūlái, come out), 出门 (chūmén, leave the house), 出生 (chūshēng, to be born — "exit life"), 出现 (chūxiàn, to appear), 出口 (chūkǒu, exit / export), 输出 (shūchū, output / export). Mandarin builds an entire family of directional verbs from 出+: 出来 (come out toward speaker), 出去 (go out away from speaker), 出去走走 (go out for a stroll). 出 is one of the foundational motion characters in CJK languages.

Japanese: on-reading シュツ (shutsu) for formal compounds — 出発 (shuppatsu, departure), 輸出 (yushutsu, export), 出席 (shusseki, attendance), 出張 (shutchō, business trip), 提出 (teishutsu, submission). Note the irregular pronunciation 出(shutsu) often gets simplified to シュッ (shut) with gemination before unvoiced consonants.

Kun-readings dominate everyday Japanese: で.る (de.ru, to come out / leave) — the most common everyday verb form, used dozens of times daily; だ.す (da.su, to put out / submit) — the transitive partner. 出口 (deguchi, exit) and 入口 (iriguchi, entrance) are signs you see at every Japanese train station, both using kun-readings.

Memory aid: a foot stepping out of a cave-mouth — the moment of leaving frozen into a character.