This is the 4631st most frequent Japanese word.
折り返し
"折り返し" means "call or reply back promptly" or "turn back."
Here, '折り返し' is used to indicate a quick return action regarding a phone call.
折り返し電話しますね。
I will call you back shortly.
In this sentence, '折り返し' refers to the turning-back action of the train at a designated location.
次駅で電車が折り返します。
The train will turn back at the next station.
'折り返し' is used here to denote replying promptly after receiving a message.