Before The Wall came down, most of what I knew was about West Germany, and learned from school. Some from friends & family & friends of the family who had spent time there. I was mostly living in SE Asia at the time. I didn't go to Europe myself until later.
But a lot of it was also historical. Habsburg / Holy Roman Empire / Protestant Reformation / German Confederation / Franco-Prussian War / etc. (Unless we want to go back further before Germany really resembled Germany at all. But just sticking with mostly modern looking DEU? Rough European political shifting about from the 1500s-early 1900's. Especially military bits which relate to the US, like the Hessian mercenaries during our revolutionary war, or US/German settlements-regions-history-customs within the US). Then a whole lot of our side of the wars from the assassination of Archduke Ferdinand until the end of the Second World War. Then things tend to get fairly sketchy until 1989.
From the 1990s onward? Not a huge amount, I couldn't hold my own in conversation with diplomats or anything, but I've been there several times. My brother lived in Stuttgart & Berlin for a few years, and I visited whenever I was in Europe (He's fluent, I'm not... My German is a truly embarrassing mix of high/low and contains random swabish where you wouldn't expect it :bag:). I worked with German aid workers after I got out of the military, ditto knew a few IDF folks who settled there and would visit them, also, although I tended to spend more time in Switzerland or Italy. Later on, in university, there are/were a helluva lot of German scholars, & artists. So I've got a general feel for the country, although very basic. To be honest, I think my son knows a great deal more. My knowledge is very scattered.