Simple wordclock project. Just flash files to your Arduino of choice (you'll need A6/A7).
Connect LEDs through apropriate resistor directly to your Arduino Pins: Eins: D1 [...] Zwölf: D12
EsIst: D0 Uhr: 13 Vor: A0 Nach: A1 Viertel: A2 Halb: A3 Zehn: A4 Fünf: A5
Button_hour: A6 Button_min: A7