The verb "to speak" translates in to German as "sprechen" or "reden".
Kannst du Deutsch sprechen = Can you speak German
No, sprechen means speak in German.
"Speaking" in German is "sprechen".
Sprechen Sie deutsch? is German for "Do you speak German?"
"Kann nicht sprechen Deutsch"
Sprechen
"Sprechen Sie fun" is a mix of German and English, with "Sprechen Sie" meaning "Do you speak" in German. However, "fun" is an English word and doesn't translate directly into German. The phrase could be interpreted as asking someone if they enjoy or understand fun, but it's not a grammatically correct or commonly used expression in either language.
Do you speak Spanish in Spain and Swedish in Sweden?
Können Sie Deutsch sprechen? (formal) Kannst du Deutsch sprechen? (to a friend or family member)
Sie sprechen Deutsch. or in a more familiar way, Du sprichst Deutsch. or Ich spreche Deutsch
Austrians speak German Österreicher sprechen Deutsch
"Do you speak in German" is "Sprechen Sie Deutsch?" (formal) or "Sprichst du Deutsch?" (informal) in German.