最初の信号を

at the first traffic light

→ 最初
phrase Rare #37,339
at the first traffic light Used when giving or asking for directions, usually followed by a direction or turning verb such as 右折する (turn right) or 曲がる (turn). The を marks the traffic light as the point where the action occurs; in short directions, the verb may be omitted.
JA: 最初の信号を右に曲がってください。
EN: Please turn right at the first traffic light.

最初の信号を右折して

Turn right at the first traffic light.

最初の信号を左へ曲がるのですか

Do I turn left at the first traffic light?

最初の信号を右に

Turn right at the first traffic light.

最初の信号を左へ曲がって下さい

Please turn left at the first traffic light.