Several parts combine into one character.

Pictograph: a tongue extending from a mouth (口 at the bottom). Oracle bone forms show the forked tip of the tongue extending upward — the character is the picture. Identical across 繁體 / 新字体 / 简体. Note 舌 is distinct from but related to 言 (speech, from earlier batch) — 言 is "what comes out of a mouth", 舌 is the organ that produces it.

Mandarin: shé, rising 2nd tone. 舌头 (shétou, tongue — the everyday word, neutral final tone), 舌尖 (shéjiān, tip of tongue — also the title of a famous Chinese food documentary 舌尖上的中国, "A Bite of China"), 口舌 (kǒushé, tongue and mouth → speech / argument). The compound 唇齿相依 (chúnchǐ xiāngyī, "lips and teeth depend on each other") expresses interdependence.

Japanese: on-reading ゼツ (zetsu) for compounds — 舌戦 (zessen, war of words), 毒舌 (dokuzetsu, sharp / poisonous tongue — used to describe a comedian who roasts others), 弁舌 (benzetsu, eloquence). Kun-reading した (shita) is the everyday word — 舌 (shita, tongue), 舌打ち (shitauchi, clicking the tongue in irritation — culturally significant gesture), 舌足らず (shitatarazu, lisp / inarticulate).

The character's phonetic role is significant — when 舌 sits on the right side of compounds it often carries a "she/zetsu/setsu" sound, leading to characters like 話 (speech, 言+舌), 活 (alive, 氵+舌), 適 (suitable). Recognizing 舌 as a phonetic component helps decode many derived characters.

The Japanese 毒舌 (dokuzetsu, "poison tongue") is positively used to describe stand-up comedians and roasters whose sharp humor is appreciated.

Memory aid: a tongue sticking out of a mouth — the most direct possible picture.