What does 何年生の時に、どんな学部で何を専攻したいか先生に聞かれましたか mean?
I tried to translate it into "What grade were you in when your teacher asked you what you wanted to major in and in what department?" but I'm not a native speaker of English myself, let alone translate Japanese

Question

What does 何年生の時に、どんな学部で何を専攻したいか先生に聞かれましたか mean?
I tried to translate it into  "What grade were you in when your teacher asked you what you wanted to major in and in what department?" but I'm not a native speaker of English myself, let alone translate Japanese

Answer

Hello,

To answer your question,　what is　「何年生の時に、どんな学部で何を専攻したいか先生に聞かれましたか 」
in English?

I would say (in English):

"What year were you in, as a college student (university student), when your professor (teacher) asked you what subject (graduate course) you wanted to major in?

学部 specifically refers to college/university 'graduate course or department (area) of study'
 So that's how (why) it translates into English in the above way.

Hope that helps.