‘-입니다.’ is added to nouns in declarative sentences. It means ‘to be’ and is used in formal settings.
저것은 교실입니다. That’s a classroom.
저것은 책상입니다. That’s a desk.
이것은 의자입니다. This is a chair.
이것은 칠판입니다. This is a blackboard.
이것은 제 연필입니다. This is my pencil
이것은 제 지우개입니다. This is my eraser.
그것은 펜입니다. It’s a pen.
그것은 필통입니다. It’s a pencil case.
그것은 컴퓨터입니다. It’s a computer.
In Korean, if you and the listener can guess (or already know) the subject of the sentence, you can omit it. For example,
선생님입니다. (I / She / He) am/is a teacher.
학생입니다. (I / She / He) am/is a student.
남자입니다. (I / She / He) am/is a man.
여자입니다. (I / She / He) am/is a woman
Omission of subject is often found in colloquial English, too:
A: “Going somewhere?”
B: “Yea. Gotta fix my car today.”
The interrogative form is ‘입니까?’
이것이 무엇입니까? What is this?
생일이 언제입니까? When is (your) birthday?
이름이 무엇입니까? What is (your) name?
전화번호가 무엇입니까? What is (your) phone number?
학생입니까? Are (you) a student?