Yes, you do.

Usually the announcements (at least for Main Station = Hauptbahnhof) is also announced in english language. There are also signs on the plattform with the name of the station.

Any most likely you will find someone speaking English if you feel the need to ask.

By the way, another indication where you are is when the S-Bahn goes underground, the main station (Hauptbahnhof) is the first underground station if you come from the airport. In so far you can just count the stations from there (Main Station - Taunusanlage - Hauptwache). All trains usually have network plans in the train.