Tek bir oda kaldı.

Yes, they are closely related, but they do different jobs here.

• bir = one / a
• tek = single / only / sole

So tek bir oda does not just mean one room. It adds emphasis:

• bir oda = a room / one room
• tek bir oda = only one room / a single room

Using both together is very common in Turkish when you want to stress that there is just one.

Here, tek means only, single, or sole.

It emphasizes that the number is limited to one. So tek bir oda strongly highlights that there is no second room available.

You can think of it as:

• tek kişi = a single person / only one person
• tek yol = the only way
• tek bir oda = only one room

Kaldı comes from the verb kalmak.

kalmak can mean things like:

• to stay
• to remain
• to be left

In this sentence, it means remained / is left.

So Tek bir oda kaldı literally works like:

• A single room remained
• more naturally in English: Only one room is left or There is only one room left

This is a very common point of confusion.

kaldı is the simple past form of kalmak. Literally, it means remained. But in Turkish, this form is often used when talking about a result that has now become true.

So in context, Tek bir oda kaldı can naturally mean:

• Only one room remained
• or, in everyday English, There is only one room left now

It often focuses on the fact that the number has gone down and the result is now one.

If you wanted a more directly present-style idea, Turkish might also use other phrasing depending on context, but kaldı is very natural here.

Turkish does not always need an equivalent of English there is / there are.

English says:

• There is only one room left

Turkish can simply say:

• Tek bir oda kaldı

Turkish often builds these ideas without a separate dummy subject like there. The sentence directly states what remained: one single room.

Oda is in its basic dictionary form here because it is the thing that remained.

• oda = room

There is no case ending because it is functioning as the subject-like element of the sentence.

Compare:

• Tek bir oda kaldı. = Only one room remained.
• Odayı gördüm. = I saw the room.
  Here oda becomes odayı because it is the definite direct object.

So in your sentence, plain oda is exactly what we expect.

Yes, Bir tek oda kaldı is also possible, and it means almost the same thing.

Both are natural:

• Tek bir oda kaldı
• Bir tek oda kaldı

The difference is mostly one of emphasis and rhythm.

Very roughly:

• tek bir oda sounds like a single room
• bir tek oda often feels like just one room

In everyday speech, both are common and understandable.

Yes. That is also correct.

• Tek bir oda kaldı = Only one room left / A single room left
• Sadece bir oda kaldı = Only one room left

The difference is nuance:

• tek bir is a bit stronger and more emphatic
• sadece is a straightforward only

All of these are natural depending on style:

• Tek bir oda kaldı.
• Sadece bir oda kaldı.
• Yalnızca bir oda kaldı.

Because Turkish normally places the finite verb at the end of the sentence.

So the structure is:

• Tek bir oda = the thing being talked about
• kaldı = the verb, placed at the end

This is very typical Turkish word order.

English:

• Only one room is left.

Turkish:

• Tek bir oda kaldı.

Of course, Turkish word order can sometimes change for emphasis, but verb-final order is the standard pattern.

Possibly, yes. Turkish often leaves out information that is obvious from context.

For example, in a hotel-booking situation, Tek bir oda kaldı may really imply:

• Otelde tek bir oda kaldı. = Only one room is left in the hotel.
• Tek bir odamız kaldı. = We have only one room left.

But if the context already makes that clear, Turkish commonly uses the shorter sentence.

A simple pronunciation guide:

• Tek ≈ teck
• bir ≈ beer (but with a shorter vowel)
• oda ≈ oh-dah
• kaldı ≈ kahl-duh

A fuller approximation:

tek beer oh-DAH KAHL-duh

A few notes:

• r in Turkish is lighter than in many English accents.
• The final ı in kaldı is the Turkish ı, which is not the same as English ee or ih. It is a dull, central vowel.
  So kaldı is not kaldi.

It has several meanings, which is why learners meet it often.

kalmak can mean:

• to stay
  
  • Evde kaldım. = I stayed at home.
• to remain / be left
  
  • Tek bir oda kaldı. = Only one room was left.
• to be delayed / to be left behind / to fail to do something, depending on context

So in your sentence, the meaning is specifically to remain / be left. Context tells you which sense is meant.