The Phrase
This German Idiom is used quite commonly. If you‘re not in the loop, you might wonder why they are talking about the train station in this conversation. They don't really.
Germans use this when they can’t make heads or tails of a situation. It literally means “I only understand train station”. You can just picture a German speaker on holiday trying to communicate with the locals but only catching this one word — train station — and then turning to their fellow vacationers shrugging:
Ich verstehe nur Bahnhof.
Examples
Also, mein Termin war um 15:00 Uhr, aber ich habe die Ärztin nicht vor 16:00 Uhr gesehen und trotzdem kam sie um 14:30 Uhr? Ich verstehe nur Bahnhof. So, my appointment was at 15:00 but I didn't see the doctor until 16:00, and yet she arrived at 14:30?
Das verstehe ich nicht. Ich habe die ganze Nacht gelernt und bin trotzdem durch den Mathe-Test gefallen. Ich verstehe nur Bahnhof. I dont understand. I studied all night and still failed my math test.