Pictograph: a mouth (口 at the bottom) with a stylized stream of sound rising from it. The horizontal lines stacked above the mouth represent the vibrating air — the act of speaking visualized. Identical across 繁體 / 新字体 / 简体 (in 简体 it transforms into 讠 when used as a left-side radical).

言 is one of the all-time most productive radicals in the script — it builds the entire vocabulary of speech, language, communication, and writing. When 言 sits on the left of a compound, the meaning is almost guaranteed to involve words: 語 / 语 (language), 說 / 说 (speak), 話 / 话 (talk / story), 讀 / 读 (read), 記 / 记 (record), 詩 (poem), 詞 (word), 課 / 课 (lesson), 試 / 试 (test), 訳 / 译 (translate), 識 / 识 (knowledge), 訴 / 诉 (sue / appeal). Spotting 言 / 讠 on the left of a character cuts the meaning space dramatically.

Mandarin: yán, rising 2nd tone. The everyday verb "to speak" is 说 (shuō), so 言 in modern Chinese feels formal/literary: 语言 (yǔyán, language), 名言 (míngyán, famous saying), 谎言 (huǎngyán, lie), 言论 (yánlùn, speech / discourse), 自言自语 (zì yán zì yǔ, talking to oneself). Notice in simplified Chinese the radical morphs to 讠 — the standalone character keeps 言.

Japanese: TWO on-readings split by Buddhist vs. Chinese tradition. ゲン (gen, kan-on) is dominant — 言語 (gengo, language), 言及 (genkyū, mention), 発言 (hatsugen, statement / utterance), 助言 (jogen, advice). ゴン (gon, go-on) survives in Buddhist-rooted compounds — 無言 (mugon, silence / no words), 言上 (gonjō, formal speech to a superior). Kun-readings: い.う (i.u, to say) — one of the most common Japanese verbs; こと (koto, word / matter / fact) — 言葉 (kotoba, word / language — note rendaku) is essential vocabulary.

Memory aid: a mouth with sound rising in waves — speech given form on paper.