公共汽车 (gōng gòng qì chē) means “bus”

More examples

她下了公共汽车，回家了。tā xià le gōng gòng qì chē huí jiā le

She got off the bus and went home.

A shared vehicle moving many passengers between regular stops on city streets.

公交车gōng jiāo chē: A city bus that picks up and drops off passengers at stops along its route.
公交gōng jiāo: A short spoken term for a public bus.

为公众按固定路线和停靠点输送乘客、在道路上营运的车辆。wèi gōng zhòng àn gù dìng lù xiàn hé tíng kào diǎn shū sòng chéng kè zài dào lù shàng yíng yùn de chē liàng

The word joins 公共 (gōnggòng, "public") with 汽车 (qìchē, "automobile"), presenting the vehicle as an automobile for general public use.

Chinese travel talk often includes the route number because different services can pass through the same area, making the number an important part of the information.