捷运是一种城市里的火车，很多人坐它上班或者上学。

捷运 is a kind of urban train that many people take to work or school.

在台湾，人们常常说捷运，在中国大陆一般说地铁。

In Taiwan, people often say 捷运, while in mainland China they usually say 地铁 (subway).