godan verb (-ru), intransitive verb, transitive verb
turn around; look back; look over one's shoulder
Physical action of turning one's head or body to look behind. Can be intransitive or transitive (e.g., 振り返って見る).
後ろから名前を呼ばれて、思わず振り返った。
When someone called my name from behind, I turned around without thinking.
彼は一度だけ肩越しに振り返って、手を振った。
He looked back over his shoulder just once and waved.
godan verb (-ru), transitive verb
look back on; reflect on; reminisce about
Metaphorical use: recalling or reflecting on past events, often with a sense of nostalgia or evaluation. Commonly used with ～を振り返る.
今年一年を振り返って、いろいろなことがあったなと思う。
Looking back on this past year, I realize a lot has happened.
彼女は青春時代を振り返りながら、微笑んだ。
She smiled while reminiscing about her youth.