The grammar points we will learn in this lesson is n desu & n da. It is used to strongly express something.
It is cold = samui n da (寒いんだ)
(He) can drink alcohol (I am suprised) = osake nomeru n da (お酒飲めるんだ)
It is used to ask a question you want to know the answer to.
When did you come to Japan = itsu nihon ni kitan desu ka