이거, 그거, 저거 — and how to ask 'what is that?'
English splits the world into 'this' and 'that'. Korean splits it three ways: 이 (this — near me, the speaker), 그 (that — near you, the listener, OR something we both already know about), 저 (that over there — far from both of us). Stick 것 ('thing') on each to get 이것 (this thing), 그것 (that thing), 저것 (that thing over there). In speech these usually shrink to 이거, 그거, 저거. The question word for 'what?' is 뭐, and you've already met it in lesson 2's 이름이 뭐예요?.
이 vs 그 vs 저 — distance from whom?
Korean's three-way split tracks who's close to the thing. 이 = close to the speaker ('this book, in my hand'). 그 = close to the listener ('that book on your desk') OR something we both already mentioned ('the book we just talked about'). 저 = far from both of us ('that building across the street'). Native speakers use 그 more loosely than English 'that' — it covers a lot of 'the [previously mentioned] X'.
이것 / 그것 / 저것 — the things themselves
Add 것 ('thing') to make a standalone pronoun. 이것 = this (one), 그것 = that (one), 저것 = that one over there. In casual / spoken Korean, these almost always contract: 이것 → 이거, 그것 → 그거, 저것 → 저거. The contracted forms are what you'll hear most. 이거 책이에요 = 'This is a book'. 저거 뭐예요? = 'What is that (over there)?'
Demonstrative + noun — no extra word needed
Put 이/그/저 directly in front of a noun: 이 책 (this book), 그 학생 (that student), 저 사람 (that person over there). No copula or particle between the demonstrative and the noun — just slap them together. 이 책이 좋아요 = 'I like this book' (literally 'as for this book, [it's] good').
뭐, 누구, 어디, 언제 — basic question words
뭐 = what (already met). 누구 = who. 어디 = where (lesson 3). 언제 = when. 얼마 = how much (price). Korean question words usually sit where the answer would sit, with the question particle 요 at the very end of the verb. 이거 뭐예요? = 'What is this?'. 저 사람이 누구예요? = 'Who is that person?'. No need for a separate 'do' helper like English.
Politeness with 사람 vs 분
사람 = person (neutral). 분 = the polite version, used for someone you're being respectful about. 저 사람이 누구예요? is fine for asking about a peer or stranger; 저 분이 누구세요? is more polite, with the honorific 세요 ending. As a learner, you'll use 사람 more often, but recognize 분 when you see it.
