Pictograph: a person (the upper portion is 大, the spread-armed adult human) standing upright on the ground (the bottom horizontal line). The picture is the verb. Identical across 繁體 / 新字体 / 简体.

立 sits at the heart of an entire family of "standing / establishing" abstractions. Beyond physical standing, it covers founding, setting up, and being positioned: 独立 (independence — "stand alone"), 成立 (to be established / to take effect), 設立 / 设立 (to set up / found), 中立 (neutrality — "stand in the middle"), 国立 (kokuritsu, national / state-run — "established by the country"), 立場 / 立场 (standpoint / position — "the spot where one stands").

Mandarin: lì, falling 4th tone. 立 alone is mostly literary; the everyday verb "to stand" is 站 (zhàn, falling tone). 立 still leads many compound abstractions: 成立 (chénglì), 独立 (dúlì), 立刻 (lìkè, immediately — "stand at the moment"), 立场 (lìchǎng, position / stance), 设立 (shèlì, to establish).

Japanese: on-reading リツ (ritsu) is dominant — 独立 (dokuritsu, independence), 設立 (setsuritsu, founding), 国立 (kokuritsu, national — as in 国立大学 national universities), 立派 (rippa, splendid / fine — "standing-faction"). Less common リュウ (ryū) in 建立 (konryū, building of a temple). Kun-readings: た.つ (ta.tsu, to stand — intransitive) and た.てる (ta.teru, to set up — transitive). 立つ / 立てる is one of the foundational intransitive/transitive verb pairs in Japanese. Also note compounds with 立 take small phonetic adjustments: 立派 (rippa) shows the 立 vowel-doubling characteristic of compounds.

立 is also a critical RADICAL — it appears at the top of characters like 章 (chapter), 童 (child), 音 (sound), 意 (meaning) — though in those cases it has the abstract sense of "set up / situated".

Memory aid: a stick figure standing on a baseline — the upright adult.