The yellow traffic light — the amber signal in traffic lights indicating caution (slow down/prepare to stop).
交差点で黄信号になったので、徐行して止まった。
The light turned yellow at the intersection, so I slowed down and stopped.
黄信号は通過してもよい場合と止まるべき場合があり判断が難しいことがある。
Sometimes it's difficult to judge whether to pass through a yellow light or stop, as it depends on the situation.
急いでいたが、黄信号だったので渡るのをやめた。
I was in a hurry, but because the light was yellow I decided not to cross.
A warning sign; an indication that something may be risky or problematic (figurative use).
売上の落ち込みは会社にとって黄信号だ。
The drop in sales is a warning sign for the company.
彼の遅刻が続くのは仕事へのモチベーション低下の黄信号かもしれない。
His repeated lateness might be a yellow flag indicating decreased motivation at work.
この数値の変動は投資家にとって黄信号と受け取られた。
This fluctuation in figures was taken as a warning sign by investors.