独轮车 (dú lún chē) means “unicycle”

More examples

我周末练习骑独轮车。wǒ zhōu mò liàn xí qí dú lún chē

I practice riding a unicycle on weekends.

A pedal-powered vehicle balanced on one wheel, with its rider above the wheel.

单轮车dān lún chē: A single-wheel vehicle used for travel while a rider keeps it balanced.

只有一个车轮、供人骑行的车。zhí yǒu yí gè chē lún gōng rén qí xíng de chē

独 (dú, "single") + 轮 (lún, "wheel") + 车 (chē, "vehicle") forms a transparent compound for a vehicle with one wheel.

The number in this word describes the wheel count, not the rider count, so it does not mean that the rider is alone.