Chú thích được viết bởi hướng dẫn viên.

A word-by-word breakdown is:

• chú thích = note, annotation, caption, explanation
• được = a passive marker here, roughly is/are
• viết = written / to write
• bởi = by
• hướng dẫn viên = tour guide / guide

So the structure is basically:

• Chú thích
  • được viết
    • bởi hướng dẫn viên
• The note/caption is written by the guide

No. In this sentence, chú thích is a fixed compound meaning annotation, note, caption, explanatory note.

Even though chú by itself can mean uncle, that meaning is not relevant here. This is very common in Vietnamese: a syllable may have one meaning by itself, but in a compound word the whole expression has a different meaning.

So here, treat chú thích as one vocabulary item.

Here, được marks the passive voice.

So:

• viết = write
• được viết = be written

That is why the sentence means is written by...

A very common learner confusion is that được can also mean to get, to receive, or to be allowed to in other contexts. But here it is not that meaning. Here it is a grammatical marker showing that chú thích is the thing receiving the action.

Not always, but very often it helps express that idea.

In Vietnamese, passive meaning can be shown in several ways, and được is one common option. It often suggests a neutral or sometimes slightly positive passive.

Compare:

• được viết = is written
• bị viết would sound odd here, because bị usually suggests something negative or unwanted

So in this sentence, được is the natural passive marker.

Bởi introduces the agent in a passive sentence, like English by.

So:

• bởi hướng dẫn viên = by the guide

However, bởi often sounds a bit formal or written. In everyday Vietnamese, people may prefer other patterns, especially:

• Chú thích do hướng dẫn viên viết.

This also means The note/caption is written by the guide, and many speakers may find it more natural.

So bởi is correct, but it can feel more formal than some alternatives.

Yes, if the agent is not important or already understood.

For example:

• Chú thích được viết. = The note/caption is written.

But this sounds less complete unless the context makes it clear who wrote it or unless the focus is only on the fact that it was written.

If you want to mention the writer, adding bởi hướng dẫn viên gives that information explicitly.

Vietnamese usually does not use articles like English a/an/the.

So:

• chú thích can mean a note, the note, notes, or the notes
• hướng dẫn viên can mean a guide, the guide, or guides

The exact meaning depends on context.

That means this sentence could be understood as:

• The caption is written by the guide
• A note is written by a guide
• Notes are written by guides

In real use, the surrounding context tells you which one is meant.

By itself, it is not marked for singular or plural.

So hướng dẫn viên can mean:

• the guide
• a guide
• guides

If Vietnamese wants to make number clearer, it can add words such as:

• một hướng dẫn viên = one / a guide
• các hướng dẫn viên = guides
• những hướng dẫn viên = guides

In your sentence, the number is left unspecified.

Just like hướng dẫn viên, chú thích is not marked for number by itself.

So it could mean:

• the note
• a note
• the caption
• captions
• annotations

If the speaker wanted to make it clearly plural, they might say:

• các chú thích = the captions / the notes
• những chú thích = some captions / notes

The structure is:

• Subject + passive marker + verb + agent

So:

• Chú thích = subject
• được = passive marker
• viết = verb
• bởi hướng dẫn viên = agent phrase

A very literal order is:

• Note/caption + is written + by guide

This is quite close to English passive word order.

A straightforward active version is:

• Hướng dẫn viên viết chú thích.
• The guide writes the note/caption.

If you want to keep the same meaning but use a more natural Vietnamese written style, another common version is:

• Chú thích do hướng dẫn viên viết.

This is not exactly the same grammar as English passive, but it expresses the same idea very naturally.

Yes, it is grammatical and understandable, especially in formal or written contexts.

However, many speakers would find these versions more natural depending on context:

• Chú thích do hướng dẫn viên viết.
• Hướng dẫn viên viết chú thích.

So your original sentence is correct, but it may sound a bit more formal or textbook-like than everyday speech.

Yes. Vietnamese verbs do not change form the way English verbs do.

So viết can correspond to:

• write
• writes
• wrote
• written

The surrounding words and context show the meaning.

In this sentence, được tells you that viết should be understood in a passive sense:

• được viết = is written

A rough English-friendly guide is:

• hướng ≈ hoo-uhng with a dipping/rising tone
• dẫn ≈ zun or yun in northern speech, with a heavy falling/glottal tone
• viên ≈ vee-uhn or vyuhn, level tone

A few important notes:

• The d in southern Vietnamese often sounds like English y
• The d in northern Vietnamese often sounds like z
• Tones matter a lot, so listening to native audio is very helpful

If you want, I can also break down the pronunciation of the whole sentence syllable by syllable.