Take the wide-armed figure you already know from 大, plant it on a single flat stroke of ground, and you get exactly what it shows: someone standing. The line beneath the figure is the whole idea — no ground, no standing. From this simple picture grew a wider family of meanings: to stand, to set something upright, and eventually to establish or found.
A piece of culture
The day a nation stood up On October 1, 1949, Mao Zedong stood atop Tiananmen and declared "中华人民共和国中央人民政府今天成立了" — "the Central People's Government of the People's Republic of China is founded today." That founding verb, 成立, is built on 立: to come into being, to stand up. The date is still China's National Day, marked every year with a flag-raising at dawn on the very square where the nation was proclaimed to "stand".
Use it in a real word
中立
zhōnglì · zung1 laap6
neutral — literally "standing in the middle"; you already know 中