geugeoseun mwoyeyo?

It breaks down like this:

• 그것 = that thing / it
• 은 = topic particle
• 뭐예요 = what is (it)? in polite speech

So the structure is roughly:

• As for that thing, what is it?

In natural English, that becomes What is that?

Korean topic particles change depending on the final sound of the word before them.

• Use 은 after a consonant
• Use 는 after a vowel

Since 그것 ends in ㅅ, which is a consonant, you use 은:

• 그것 + 은 → 그것은

This is the same pattern as:

• 책은 = as for the book
• 학교는 = as for the school

은 marks the topic of the sentence. It tells the listener what the sentence is about.

So 그것은 뭐예요? is literally something like:

• As for that, what is it?

In many cases, English does not mark topic separately, so we simply translate it as What is that?

In conversation, 은/는 can also add a slight sense of contrast depending on context, but here it is just the normal topic marker.

뭐 is the common spoken form of 무엇, and both mean what.

So these are basically the same in meaning:

• 무엇이에요?
• 뭐예요?

But there is a style difference:

• 뭐예요? = more natural and common in everyday speech
• 무엇이에요? = more formal or careful

Most Korean speakers would normally say 뭐예요? in ordinary conversation.

Yes. It comes from 무엇이에요 through a shortened spoken form.

A common way to think of it is:

• 무엇이에요 → 뭐예요

You do not need to memorize every sound change in detail at first. The important point is:

• 무엇 and 뭐 both mean what
• 뭐예요? is the very common polite spoken form

Yes, very often.

Korean frequently drops words that are understood from context. If you are pointing at something or the situation makes it obvious, you can simply say:

• 뭐예요? = What is it? / What is that?

Using 그것은 can sound more explicit, but in real conversation Korean often prefers the shorter version when the topic is already clear.

뭐예요? is polite and appropriate in many everyday situations.

You might compare it with:

• 뭐야? = casual, used with close friends or younger people
• 뭡니까? or 무엇입니까? = more formal
• 뭐예요? = polite, neutral, very common

So 그것은 뭐예요? is a safe and useful sentence for everyday polite speech.

A careful romanization would be:

• geugeoseun mwoyeyo?

But actual pronunciation in natural speech is a bit smoother than that.

A beginner-friendly guide is:

• 그것은 ≈ geu-geo-seun
• 뭐예요 ≈ mwo-ye-yo

Do not rely too heavily on romanization, though. It is much better to learn the Korean sounds directly.

Not exactly. Korean has a three-way distinction that English often does not show clearly:

• 이것 = this thing, near the speaker
• 그것 = that thing, near the listener or already known in the conversation
• 저것 = that thing over there, far from both speaker and listener

So depending on the situation, English that could be either:

• 그것
• 저것

Learners often translate both simply as that, but Korean makes a more precise distinction.

Yes, and that is very common.

• 그것은 뭐예요? = topic-marked form
• 그게 뭐예요? = subject-marked form using the contracted form 그것이 → 그게

In everyday speech, 그게 뭐예요? often sounds more natural than the full 그것은 뭐예요?, depending on context.

Very roughly:

• 그것은 뭐예요? = As for that, what is it?
• 그게 뭐예요? = What is that?

Both are correct, but the shorter form is very common in real conversation.

In writing, you normally use a question mark:

• 그것은 뭐예요?

In speech, the sentence is understood as a question because of:

• the question word 뭐 = what
• rising or questioning intonation

So even without thinking about punctuation, Korean listeners will recognize it as a question from the wording and tone.