The expression isn't really so idiomatic. It literally translates to: one will see you (around). I think the implied idea would be that we're not going anyway (far away) and will bump into each other in the near future. I live in NRW, you can use this phrase in casual conversation. Although ciao, or tschüss are more common.
"Nordrhein-Westfalen" in English "North Rhine-Westphalia". The most populous state of Germany, home to the Ruhr region the largest urban agglomeration in Germany and third-largest in the European Union (copied from Wikipedia).
Another abbreviation for a German state is "MV" for "Mecklenburg-Vorpommern" (Mecklenburg-West Pomerania), other states are normally not abbreviated in speech. "MV" and "NRW" are the exceptions there. They are like DC in this respect.