Nắp chai ở gần chai nhựa.

Because the two instances of chai do different jobs:

• nắp chai = bottle cap

  • nắp = lid, cap
  • chai = bottle
  • Together, this literally means the cap of a bottle.

• chai nhựa = plastic bottle

  • chai = bottle
  • nhựa = plastic
  • Together, this means plastic bottle.

So the sentence is not repeating the same phrase. One chai belongs to nắp chai, and the other is the main noun in chai nhựa.

Vietnamese noun phrases often work differently from English.

In nắp chai:

• nắp is the main noun: cap/lid
• chai specifies what kind of cap: bottle

So Vietnamese says something like cap bottle, where English says bottle cap.

This is very common in Vietnamese. The main thing comes first, and the specifying noun comes after it.

ở gần means to be near or to be located near.

In this sentence:

• ở gives a sense of location: to be at / to be located
• gần means near

So ở gần together means is near.

That is why Nắp chai ở gần chai nhựa means The bottle cap is near the plastic bottle.

Yes, in many situations you can.

• Nắp chai ở gần chai nhựa = more explicitly The bottle cap is located near the plastic bottle
• Nắp chai gần chai nhựa = The bottle cap is near the plastic bottle

Both are understandable and natural.
Adding ở makes the location relationship a little clearer or fuller.

Vietnamese often does not use a direct equivalent of English is in the same way.

English needs a linking verb in sentences like:

• The bottle cap is near the plastic bottle

Vietnamese can express this idea without a separate linking verb like English does. Instead, location is expressed with words like:

• ở = to be at / located at
• gần = near

So Vietnamese grammar does not require a one-word equivalent of English is here.

Vietnamese does not have articles like English a/an and the.

So:

• nắp chai could mean a bottle cap or the bottle cap
• chai nhựa could mean a plastic bottle or the plastic bottle

The exact meaning depends on context.

If the meaning shown to the learner is The bottle cap is near the plastic bottle, that is a natural English translation, but Vietnamese itself does not mark the directly here.

Because in Vietnamese, descriptive words that classify or specify a noun often come after the noun.

So:

• chai nhựa = plastic bottle
  • literally: bottle plastic

This is normal Vietnamese word order.

Compare:

• English: plastic bottle
• Vietnamese: chai nhựa

The noun usually comes first, and the material or descriptive element comes after it.

In normal context, chai nhựa means plastic bottle.

That is because:

• chai = bottle
• nhựa = plastic

So the most natural reading is a bottle made of plastic.

In some contexts, Vietnamese compounds can be flexible, but here plastic bottle is by far the expected meaning.

Classifiers in Vietnamese are common, but they are not always required.

You might also hear:

• Cái nắp chai ở gần cái chai nhựa.

Here, cái is a classifier for objects.

However, in many simple statements, especially when speaking naturally or describing things, classifiers can be omitted if the meaning is already clear.

So:

• Nắp chai ở gần chai nhựa is fine.
• Adding classifiers would make it sound a bit fuller, but they are not necessary here.

It can mean either cap or lid, depending on the object and context.

• For a bottle, nắp chai is usually best translated as bottle cap
• For other containers, nắp may be translated as lid

So nắp is a broader word than English cap alone. The context tells you which English word fits best.

The structure is:

• Nắp chai = subject noun phrase
• ở gần = location expression
• chai nhựa = reference object/location target

So the pattern is roughly:

[thing] + ở gần + [other thing]

Examples of the same pattern:

• Con mèo ở gần cái bàn. = The cat is near the table.
• Cuốn sách ở gần cửa sổ. = The book is near the window.

This is a useful pattern for describing location.

A careful pronunciation would be roughly:

• Nắp chai ở gần chai nhựa

A learner should especially notice:

• nắp has a short vowel and a final p stop
• ở has the hỏi tone
• gần has the huyền tone
• nhựa has the nặng tone on nhự

The exact pronunciation depends on dialect, but the biggest learner challenge is usually the tones and the final consonants.

Yes. Grammatically, Vietnamese leaves definiteness open unless context makes it clear.

So this sentence could match several English translations, such as:

• The bottle cap is near the plastic bottle
• A bottle cap is near a plastic bottle
• The bottle cap is near a plastic bottle

Context decides which one is best. English forces you to choose articles, but Vietnamese often does not.