Translation:Please answer the three questions.
A helping verb (or auxiliary verb) is used together with another verb to add meaning to the verb.
Sorry, I had a mistake in my original post. I edited it so maybe it makes more sense now. "Kudasai" is the helping verb, which you can use with any -te form verb to mean "please do ~". When you use it with -te form verbs, it's recommended to write it in kana.
Actually "Mondai" has two meanings, "question" and "problem". But the meaning of "Mondai" question is different from that of "Shitsumon" question. When the questioner knows the answer (ex. Quiz show, examinations), the question is "Mondai". The question of which the questioner also does not know the answer is "Shitumon".