To ask about someone's job, say What do you do? Answer with I am a and your job.
Asking about jobs
What do you do? — What do you do? I am a nurse.
Asking about languages
To ask about someone's languages, say What languages do you speak? Answer by naming the languages.
What languages do you speak? — What languages do you speak? I speak Spanish and English.
Try it: A: ___ B: I am a driver. Which question does B answer? (What do you do? / What languages do you speak? / Where do you live?) Answer: What do you do? — A job answers What do you do?What languages do you speak? needs language names, and Where do you live? asks for a place — B names a job, not a language or a place.
Try it: Hiroshi: ___ Yasmin: I speak English and Persian. Which question does Yasmin answer? (What languages do you speak? / What do you do? / How old are you?) Answer: What languages do you speak? — Two language names answer What languages do you speak? A job name answers What do you do? instead, and an age answers How old are you?
Try it: A: What do you do? B: ___ Choose B's answer. (I am a teacher. / I speak French. / I am from Haffenville.) Answer: I am a teacher. — What do you do? asks about a job, so the answer names a job: I am a teacher.I speak French is a language answer, and I am from Haffenville answers Where are you from?