首班车 (shǒu bān chē) means “first bus”

More examples

放假时我们常乘坐首班车去外地游玩。fàng jià shí wǒ men cháng chéng zuò shǒu bān chē qù wài dì yóu wán

During vacations, we often take the first bus to visit places outside the city.

The opening run on a route, before the later scheduled services follow.

头班车tóu bān chē: A casual spoken term for the first bus or train running on a route that day.

当天开始运行的第一班车或第一趟列车，也可泛指当天的始发便。dàng tiān kāi shǐ yùn xíng de dì yì bān chē huò dì yí tàng liè chē yě kě fàn zhǐ dàng tiān de shǐ fā biàn

首 (shǒu, "first") + 班 (bān, "scheduled service") + 车 (chē, "vehicle") form a compound for the vehicle that begins the day's service.

The time is route-specific, so timetable information matters when arranging an early trip.