about German language.
If there are 12 different languages in the German language in Germany, does the one German ok with learning the rest?
12 languages? you mean dialects? there are more than 12 dialects in germany i guess.
but the german you are learning on duolingo is standard german. every german speaks standard german as well since this is the official language. we have to speak it in school starting 1. grade elementary school so we get used to it. everyone will understand you with this.