Thợ máy siết chặt gương chiếu hậu.

Thợ máy literally means something like machine worker or machine repair worker. In many everyday contexts, it is translated as mechanic.

In this sentence, because the object is gương chiếu hậu and that is something on a vehicle, mechanic is the most natural translation.

Depending on context, thợ máy can sometimes be broader than English mechanic, and could refer to someone who works with or repairs machinery in general.

Because Vietnamese usually follows Subject – Verb – Object, just like English.

So here:

• thợ máy = the subject
• siết chặt = the verb
• gương chiếu hậu = the object

That is why the sentence is structured as:

• The mechanic
  • tightens/tightened
    • the rear-view mirror

Vietnamese does not use articles the way English does.

A bare noun like thợ máy can mean:

• a mechanic
• the mechanic

And gương chiếu hậu can mean:

• a rear-view mirror
• the rear-view mirror

The exact meaning depends on context.

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

• một = a, one
• này = this
• đó/kia = that
• a classifier such as cái or chiếc

For example:

• Một thợ máy siết chặt cái gương chiếu hậu này
  = A mechanic tightens this rear-view mirror

That is a very common question.

On its own, chặt can indeed mean to chop/cut in other contexts. But in siết chặt, it is not being used that way.

Here:

• siết = to tighten, clamp, squeeze
• chặt = tight, firm, securely

So siết chặt means to tighten firmly or to tighten securely.

This kind of combination is common in Vietnamese: a main verb is followed by another word that adds the result or degree.

So siết chặt is stronger and more complete than just siết.

It is a compound noun meaning rear-view mirror.

You can break it down like this:

• gương = mirror
• chiếu hậu = rear-view, reflecting backward

More literally, it is something like mirror for looking/reflecting to the rear.

You do not need to translate each part separately in normal English, though. As a whole, gương chiếu hậu is simply the normal Vietnamese term for rear-view mirror.

Because Vietnamese often builds noun phrases by putting the main noun first and the describing part after it.

So:

• gương = the main noun, mirror
• chiếu hậu = the description, rear-view

This is very normal in Vietnamese. English often uses:

• adjective + noun, as in rear-view mirror
• or noun + of/for + noun in some cases

Vietnamese usually does not need a word like of here.

Because classifiers are often omitted, especially when the noun is a direct object after a verb and the sentence is simply stating an action.

So siết chặt gương chiếu hậu is perfectly natural.

If you want to sound more specific or more conversational, you could add a classifier:

• siết chặt cái gương chiếu hậu
• siết chặt chiếc gương chiếu hậu

Both mean roughly the same thing, but with a more explicitly marked noun.

Very roughly:

• cái is a very common general classifier for objects
• chiếc is often used for individual items, vehicles, and some physical objects, and can sound a bit more natural with things like mirrors

You do not know from this sentence alone.

Vietnamese verbs do not change form for tense the way English verbs do. The bare verb siết chặt can refer to different times depending on context.

Possible English translations include:

• The mechanic tightens the rear-view mirror
• The mechanic is tightening the rear-view mirror
• The mechanic tightened the rear-view mirror

If Vietnamese wants to make the time or aspect clearer, it can add markers such as:

• đang = be doing, in progress
• đã = did, already
• sẽ = will

Examples:

• Thợ máy đang siết chặt gương chiếu hậu = The mechanic is tightening the rear-view mirror
• Thợ máy đã siết chặt gương chiếu hậu = The mechanic tightened / has tightened the rear-view mirror
• Thợ máy sẽ siết chặt gương chiếu hậu = The mechanic will tighten the rear-view mirror

Yes, you could, but the meaning becomes a little less explicit.

• siết = tighten
• siết chặt = tighten firmly / tighten securely

Using chặt emphasizes that the mirror is made tight and secure, not just adjusted a little.

So siết chặt is a very natural choice when talking about fastening a part properly.

In normal usage, gương chiếu hậu is the standard term for a rear-view mirror, especially on a car or motorcycle.

So when Vietnamese speakers hear gương chiếu hậu, they usually think of the mirror on a vehicle, not just any mirror located at the back of something.

If needed, context can make it even clearer:

• gương chiếu hậu xe máy = motorcycle rear-view mirror
• gương chiếu hậu ô tô = car rear-view mirror

Vietnamese is pronounced syllable by syllable, and each syllable has its own tone.

The sentence has these syllables:

• thợ
• máy
• siết
• chặt
• gương
• chiếu
• hậu

Tone-wise:

• thợ = heavy, low tone
• máy = rising tone
• siết = rising tone
• chặt = heavy, low tone
• gương = level tone
• chiếu = rising tone
• hậu = heavy, low tone

A learner should especially pay attention to:

• the contrast between máy / siết / chiếu and the nặng-tone words
• the vowel in gương
• the final consonants in siết and chặt

If the tones are wrong, Vietnamese listeners may still guess from context, but accurate tones make a big difference.

Yes. The sentence itself does not say whose mirror it is.

Gương chiếu hậu here just means rear-view mirror. Ownership or association is left to context.

If Vietnamese wants to specify it, it can add more words:

• gương chiếu hậu của xe = the vehicle’s rear-view mirror
• gương chiếu hậu của anh ấy = his rear-view mirror
• gương chiếu hậu xe máy = the motorcycle rear-view mirror

So the basic sentence is natural and complete, but it leaves some details unstated unless they matter.