KanjiJLPT N1
Phrase

phrase, clause, sentence, passage, paragraph, counter for haiku

Mnemonic

Deep inside a cavern, you open your mouth to shout — but the echo rearranges every word into a perfect phrase. Each syllable bounces off the stone walls and returns as a polished line of haiku, as if the cavern itself is composing poetry with your mouth's raw sound.
Additional thoughts
Picture the cavern's curved shape (勹) wrapping around the mouth (口) — the cave literally encloses your voice, shaping raw sound into refined phrases. The cavern is the poet; the mouth is its instrument.
Quick recall
A cavern catches your mouth's shout and echoes it back as a perfect phrase.

Details

The keyword for 句 is phrase. This kanji refers to a unit of language, specifically a clause, sentence, or phrase — a meaningful grouping of words. It is commonly used in the context of poetry, particularly in reference to the lines of a haiku, and also appears in grammatical discussions to denote distinct segments of speech or writing. More broadly, it can indicate any short, well-formed expression or passage of text.
On'yomi