Quầy hành lý thất lạc ở trong sảnh đến.

Vietnamese noun phrases usually go from the main noun first to the describing words after it.

So in quầy hành lý thất lạc:

• quầy = counter / desk
• hành lý thất lạc = lost luggage

Together, it means the lost luggage counter or the lost baggage desk.

A useful way to see it is:

• quầy = the kind of thing it is
• hành lý thất lạc = what kind of counter

This is very common in Vietnamese:

• bàn ăn = dining table
• phòng ngủ = bedroom
• quầy thông tin = information desk

So Vietnamese often builds noun phrases by putting the main item first and the function/type after it.

Quầy means a counter, service desk, or booth-like station, especially in public places such as airports, banks, or stores.

In this sentence, quầy refers to the physical service point where you go for help about lost baggage.

Common examples:

• quầy vé = ticket counter
• quầy lễ tân = reception desk
• quầy thông tin = information desk

So quầy is not the whole office or department; it usually suggests the customer-facing desk or counter.

Because:

• hành lý = luggage / baggage
• thất lạc = lost / misplaced

So hành lý thất lạc literally means misplaced luggage or lost baggage.

The phrase thất lạc is a fairly formal and common word for things that have gone missing, especially in public-service or official contexts.

For example:

• hành lý thất lạc = lost baggage
• đồ thất lạc = lost property
• trẻ bị thất lạc = a lost child / a child separated from others

Both can relate to something being lost, but they are not used in exactly the same way.

• mất is very common and broad. It can mean lost, missing, or even gone.
• thất lạc is more formal and often used for things that were unintentionally separated, misplaced, or not delivered correctly.

In an airport context, hành lý thất lạc sounds very natural because it is the standard formal expression for lost baggage.

Compare:

• Tôi bị mất ví. = I lost my wallet.
• Hành lý của tôi bị thất lạc. = My baggage was lost / misplaced.

So in this sentence, thất lạc fits the formal airport setting better than plain mất.

All three are possible in many situations, but they give slightly different feels.

• ở = at / in / located at
• trong = inside / in
• ở trong = located inside

So ở trong sảnh đến emphasizes that the counter is inside the arrivals hall.

Compare:

• Quầy hành lý thất lạc ở sảnh đến. = The lost luggage counter is at/in the arrivals hall.
• Quầy hành lý thất lạc trong sảnh đến. = The lost luggage counter is inside the arrivals hall.
• Quầy hành lý thất lạc ở trong sảnh đến. = The lost luggage counter is located inside the arrivals hall.

In everyday speech, ở trong is very natural and common.

No. Vietnamese often does not use a direct equivalent of is in location sentences.

In English, you say:

• The lost luggage counter is in the arrivals hall.

In Vietnamese, the structure is more like:

• [thing] + [location marker] + [place]

So:

• Quầy hành lý thất lạc = the lost luggage counter
• ở trong = located in / inside
• sảnh đến = arrivals hall

This is completely normal Vietnamese sentence structure. You do not need a separate verb like is here.

Sảnh means hall, lobby, or a large open indoor area.

đến means arrival or arriving, depending on context.

So sảnh đến means arrivals hall.

At airports, you may also hear related expressions such as:

• ga đến = arrivals terminal / arrival terminal area
• khu đến = arrivals area
• sảnh đi = departures hall
• khu đi = departures area

So sảnh đến is a natural airport phrase for the hall where arriving passengers come out.

Vietnamese does not usually use articles like a, an, and the the way English does.

Whether something means a counter, the counter, or that counter depends on context.

So Quầy hành lý thất lạc can mean:

• a lost luggage counter
• the lost luggage counter

In this sentence, because it sounds like directional or informational language in an airport, English naturally translates it as the lost luggage counter.

If Vietnamese wants to be more specific, it can add words such as:

• cái quầy đó = that counter
• quầy này = this counter
• một quầy = a counter

But in many cases, no article is needed.

It can be understood as either luggage in general or baggage collectively. Vietnamese nouns usually do not have a built-in singular/plural distinction the way English nouns often do.

So hành lý can refer to:

• one piece of luggage
• several pieces of luggage
• baggage in general

Context tells you what is meant.

This is why hành lý thất lạc works well as a general expression meaning lost baggage.

If you really want to make plurality clear, Vietnamese can add words like:

• các kiện hành lý = the pieces of luggage / baggage items
• một kiện hành lý = one piece of luggage

Yes. Vietnamese can often move the location phrase around, though some versions sound more natural in certain contexts.

Original:

• Quầy hành lý thất lạc ở trong sảnh đến.

Possible alternative:

• Quầy hành lý thất lạc nằm trong sảnh đến.

Here, nằm adds a stronger sense of physical location, like is located in.

You could also say:

• Ở trong sảnh đến có quầy hành lý thất lạc.

That means something like There is a lost luggage counter in the arrivals hall.

So the original sentence is natural, but other wordings are possible depending on whether you want to emphasize:

• the counter itself
• its location
• the existence of the counter

A careful pronunciation would be something like:

• Quầy
• hành lý
• thất lạc
• ở trong
• sảnh đến

A few pronunciation notes that English speakers often find helpful:

• quầy has a rising-like tone shape depending on dialect; pay attention to the vowel combination.
• hành and sảnh have different tones, so do not flatten them.
• lý and đến both carry clear tones and should not be reduced like unstressed English syllables.
• Vietnamese is syllable-timed, so each syllable is pronounced more clearly than in English.

In natural speech, the phrase may flow smoothly, but the syllables still remain relatively distinct:

• Quầy hành lý thất lạc ở trong sảnh đến.

If you want to sound natural, focus especially on:

1. saying every syllable clearly,
2. keeping the tones accurate,
3. not swallowing the final consonants in words like thất, lạc, and đến.