chekeu-inhal ttae sinbunjeungeul boyeo juseyo.

-할 때 means when doing or at the time of doing.

So:

• 체크인하다 = to check in
• 체크인할 때 = when checking in / at check-in

Here, 하다 changes to 할 before 때.

A very common pattern is:

• verb stem + -(으)ㄹ 때 = when doing something

Examples:

• 먹을 때 = when eating
• 갈 때 = when going
• 체크인할 때 = when checking in

Because Korean usually does not put the dictionary form directly before 때.

Instead, you use the modifier form:

• 하다 → 할
• so 체크인하다 → 체크인할 때

This is similar to how Korean often changes a verb before a noun-like word.

So:

• 체크인하다 = to check in
• 체크인할 때 = when checking in

Using 체크인하다 때 would sound ungrammatical.

신분증 means ID or identification card/document.

It can refer to things like:

• a passport
• a driver’s license
• a resident card
• another official photo ID

It is made of:

• 신분 = identity/status
• 증 = certificate/card/document

So the overall sense is identification document.

을 marks the direct object of the verb.

In this sentence, the thing being shown is the ID, so:

• 신분증을 = ID + object marker
• 보여 주세요 = please show

So the structure is:

• 신분증을 보여 주세요 = Please show your ID.

Because 신분증 ends in a consonant, it takes 을. If a noun ends in a vowel, it takes 를.

Examples:

• 여권을 보여 주세요 = Please show your passport.
• 티켓을 보여 주세요 = Please show your ticket.
• 주소를 알려 주세요 = Please tell me the address.

보여 주세요 comes from 보여 주다, which means to show (something to someone).

So:

• 보다 = to see/look
• 보이다 / 보여 주다 are related to making something seen
• 보여 주다 = to show

In this sentence:

• 신분증을 보여 주세요 = Please show your ID.

If you said 보세요, it would usually mean please look or please see, not please show.

So:

• 보세요 = please look
• 보여 주세요 = please show

주세요 makes the sentence a polite request: please do ...

So:

• 보여 주세요 = please show
• literally, it has the feeling of give/show it, please

This is one of the most common polite request forms in Korean.

Compare:

• 보여 줘 = show me / show it to me (casual)
• 보여 주세요 = please show me / please show it (polite)
• 보여 주십시오 = please show it (more formal)

In meaning, no real difference. Both mean the same thing.

The difference is mainly spacing style:

• 보여 주세요 = spaced form
• 보여주세요 = commonly written together

In teaching materials, you will often see 보여 주세요 because it makes the grammar easier to notice:

• 보여 주다
  • 세요/주세요

In everyday writing, 보여주세요 is also very common.

So both are acceptable, and learners should recognize both.

Korean often omits the subject when it is obvious from context.

In this sentence, the listener is understood:

• 체크인할 때 신분증을 보여 주세요.
• Please show your ID when checking in.

The implied subject is basically you, but Korean does not need to say it.

A more explicit version could be:

• 손님은 체크인할 때 신분증을 보여 주세요. = As for the guest, please show your ID when checking in.

But in real Korean, leaving the subject out is much more natural.

It is polite standard Korean.

The key marker is 주세요, which is polite and commonly used in:

• hotels
• airports
• stores
• restaurants
• customer service situations

It is not super formal, but it is polite and appropriate for speaking to customers.

Rough comparison:

• 보여 줘 = casual, informal
• 보여 주세요 = polite, normal service language
• 보여 주십시오 = more formal, official, stiff

So this sentence sounds natural in travel or hospitality situations.

Yes. That sounds very natural.

좀 often softens a request, similar to making it sound less direct.

So:

• 신분증을 보여 주세요. = Please show your ID.
• 신분증을 좀 보여 주세요. = Please show your ID, please / Could you show your ID?

In service situations, 좀 can make the sentence sound a little gentler.

체크인 is a loanword from English check-in, written in Korean pronunciation.

This is very common in modern Korean, especially for travel, hotels, airports, and technology.

So:

• 체크인하다 = to check in
• 체크아웃하다 = to check out

Even though it comes from English, it behaves like a Korean noun and combines with 하다 to make a verb.

This pattern is extremely common:

• 예약하다 = to reserve/book
• 확인하다 = to confirm/check
• 체크인하다 = to check in

A natural pronunciation is close to:

체크인할 때 신분증을 보여 주세요 → che-keu-in-hal ttae sin-bun-jeung-eul bo-yeo ju-se-yo

A few notes:

• 때 has a tense ㄸ sound, so it is ttae, not just dae
• 신분증 is pronounced roughly sin-bun-jeung
• 보여 sounds like bo-yeo

If you say it smoothly, it will sound something like:

체크인할 때 신분증을 보여주세요

Yes. That is a very natural English translation.

Even though the Korean verb is literally show, in service contexts it often corresponds to English expressions like:

• Please show your ID
• Please present your ID
• Please provide your ID at check-in

So the Korean is straightforward, but the best English wording can vary depending on context and tone.