Geography

What do conventional symbols represent?

主動詞是to represent，所以現在式的提問法是用倒裝的do。

I guess you may be asking for the definition of "conventional symbols." Conventional in this context means "common or customary usage", and symbols are "signs." In Chinese, the phrase means 常用（慣用）標誌.

For example, on maps, an airplane is used to represent an airport, a ferry with lines to mark ferry routes, a bus to indicate the terminus.