Ich spreche kein Deutsch. (Lit. I speak no German). Or: Ich kann kein Deutsch (sprechen). I can`t (speak) German. You don`t have to say "speak", as it is commonly understood, what you are referring to. Hence, to ask "do you speak English, one can simply say "can you English?" or "kannst du Englisch?"
In Germany you speak usually the German language.
Does he speak German = Spricht er Deutsch
No she doesn't speak German.
How do you speak German = Wie spricht man Deutsch
They are German so they speak German to each other.
People in Vienna speak Viennese German.
No, sprechen means speak in German.
Does he speak German = Spricht er Deutsch
Alpine people typically speak the language of the country they are from, such as German, French, Italian, or Romansh in Switzerland, German in Austria, and Italian in Italy. Additionally, English is often spoken in tourist areas.
There are gnomes that speak German fluently because they are german. Or they simply studied it.
"Do you speak in German" is "Sprechen Sie Deutsch?" (formal) or "Sprichst du Deutsch?" (informal) in German.
German is not the official language in Estonia, but some Estonians surely know how to speak German.