The kanji 効 (効) primarily conveys the meaning of "effect," "efficacy," "result," or "benefit." It refers to the outcome or impact of an action, treatment, or intervention. It implies a positive or desirable result, though the specific connotation depends on the context.

・On-yomi (音読み): こう (kō) ・Kun-yomi (訓読み): き（く） (ki(ku))

⚫︎ 効果 (kōka) Translation: effect; effectiveness ⚫︎ 効能 (kōnō) Translation: efficacy; medicinal properties ⚫︎ 薬が効く (kusuri ga ki(ku)) Translation: The medicine works; The medicine is effective

The kanji 効 (効) is a phono-semantic compound (形声文字 - keisei moji). The semantic component is 　力 (chika・chikara), meaning "power" or "strength". The phonetic component is 交 (kō), which suggests the pronunciation of the kanji. Originally, it depicted the idea of power and force, and through time, it extended to represent the effect or influence produced by that power. It developed to represent the efficacy or effect of something.