Internet cáp quang có tốc độ cao.

Cáp quang means fiber-optic cable.

• cáp = cable
• quang = light / optical

So internet cáp quang means fiber-optic internet. In natural English, we usually say fiber internet or fiber-optic internet.

Vietnamese often uses Internet as a borrowed international word. In everyday writing, you may also see internet with a lowercase i.

This is very common with modern technology vocabulary in Vietnamese. So in this sentence, Internet cáp quang simply means fiber-optic internet.

Here, có means has.

So the structure is:

• Internet cáp quang = fiber-optic internet
• có = has
• tốc độ cao = high speed

Literally, the sentence is:

Fiber-optic internet has high speed.

In smoother English, that becomes:

Fiber-optic internet has high speed or Fiber-optic internet is fast.

Because the sentence is expressing possession of a quality, not simple identity.

• là is often like is / am / are when linking one thing to another noun or category.
• có means to have.

Here, Vietnamese says the internet has a high speed:

Internet cáp quang có tốc độ cao.

Using là here would sound unnatural. Vietnamese prefers có tốc độ cao rather than something like là tốc độ cao.

Tốc độ cao means high speed.

• tốc độ = speed
• cao = high

So this is a noun phrase:

• tốc độ = the speed
• cao describes that speed as high

Vietnamese often places descriptive words after the noun, so tốc độ cao is literally speed high.

In Vietnamese, adjectives usually come after the noun they describe.

So:

• tốc độ cao = high speed
• literally: speed high

This is a very common Vietnamese pattern:

• nhà lớn = big house
• xe mới = new car
• giá rẻ = cheap price / low price

So tốc độ cao follows normal Vietnamese word order.

Yes, it is understandable and natural enough, especially in an informational or promotional context.

However, depending on context, Vietnamese speakers might also say things like:

• Internet cáp quang có tốc độ rất cao. = Fiber-optic internet has very high speed.
• Internet cáp quang rất nhanh. = Fiber-optic internet is very fast.
• Mạng cáp quang có tốc độ cao. = Fiber-optic network has high speed.

Your sentence is perfectly fine, especially for learning basic structure.

Yes. That is a very natural alternative.

Compare:

• Internet cáp quang có tốc độ cao.
  = Fiber-optic internet has high speed.

• Internet cáp quang rất nhanh.
  = Fiber-optic internet is very fast.

The first sounds a little more formal or technical because it talks about speed as a noun.
The second is simpler and more conversational.

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

So:

• Internet cáp quang can mean fiber-optic internet, the fiber-optic internet, or fiber internet, depending on context.

Vietnamese often leaves that information unstated unless it is important to be specific.

No. A classifier is not needed here.

Classifiers are usually used with countable nouns when you are specifying number or identifying a particular item, for example:

• một cái bàn = a table
• hai chiếc xe = two vehicles

But Internet cáp quang is not being counted here. It is a general subject, so no classifier is used.

The pattern is:

Subject + có + noun phrase

In this sentence:

• Internet cáp quang = subject
• có = has
• tốc độ cao = noun phrase functioning as the thing it has

So the full structure is:

Fiber-optic internet + has + high speed

This is a useful pattern in Vietnamese:

• Điện thoại này có pin tốt. = This phone has a good battery.
• Con đường này có chiều dài lớn. = This road has a great length.
• Máy tính này có hiệu năng cao. = This computer has high performance.

A rough pronunciation guide is:

In-tơ-nét cáp quang có tốc độ cao

Very approximate English-style help:

• Internet ≈ in-tuh-net
• cáp quang ≈ gahp kwahng
• có ≈ gaw
• tốc độ ≈ tohk doh
• cao ≈ kow

A few notes:

• c, k, q are pronounced as hard k-type sounds in many contexts.
• qu in quang sounds roughly like kw.
• Vietnamese tones matter, so the real pronunciation is more than just consonants and vowels.

Not perfectly. A word-for-word translation is:

Fiber-optic internet has high speed.

That is understandable English, but more natural English would usually be:

• Fiber-optic internet is fast.
• Fiber-optic internet has a high speed.
• Fiber internet offers high speeds.

So the Vietnamese structure is normal for Vietnamese, even if the best English translation may be slightly different.