Zaštiti luster ćebetom.

Zaštiti is the singular imperative of the verb zaštititi, meaning protect.

So the sentence is giving a command or instruction to one person:

• Zaštiti... = Protect...

This is the form you would use when telling one person to do it.

Related forms:

• zaštititi = to protect
• zaštiti! = protect! (to one person)
• zaštitite! = protect! (to more than one person, or polite singular)

This is about aspect, which is very important in Serbian verbs.

• zaštititi is perfective
• štititi is imperfective

In commands like this, Serbian often uses the perfective imperative when the speaker wants the action to be done as a single complete act:

• Zaštiti luster ćebetom. = Protect the chandelier with a blanket.
  (do it now / make sure it gets protected)

If you used štiti, it would sound more like keep protecting or protect in a general/ongoing sense.

Luster is the direct object, so it is in the accusative case.

But for many masculine inanimate nouns in Serbian, the accusative singular looks exactly the same as the nominative singular.

So:

• nominative: luster
• accusative: luster

That is why it appears unchanged.

Compare:

• Vidim luster. = I see the chandelier.
• Zaštiti luster. = Protect the chandelier.

If it were a masculine animate noun, the accusative would usually look different.

Because it is in the instrumental case.

In this sentence, ćebetom tells you the means/tool/material used to do the action:

• ćebetom = with a blanket

The base noun is:

• ćebe = blanket

Its instrumental singular is:

• ćebetom

So:

• Zaštiti luster ćebetom. = Protect the chandelier with a blanket.

This is a very common use of the instrumental in Serbian.

Not exactly.

In this sentence, the natural form is simply:

• ćebetom = with a blanket / using a blanket

That is the normal instrumental of means.

Sa ćebetom literally means with a blanket too, but it often sounds more like in the company of or just a less direct way of expressing accompaniment. For tools or means, Serbian usually prefers the bare instrumental without sa:

• Pišem olovkom. = I write with a pencil.
• Pokrij ga ćebetom. = Cover it with a blanket.

So here, ćebetom is the most natural choice.

Because Serbian does not have articles like English a/an/the.

So luster can mean:

• a chandelier
• the chandelier

Which one is meant depends on context.

The same applies to ćebe:

• a blanket
• the blanket

English forces you to choose an article, but Serbian usually does not.

Yes. Serbian word order is more flexible than English because case endings show the grammatical role.

The neutral order here is:

• Zaštiti luster ćebetom.

But other orders are possible, depending on emphasis:

• Ćebetom zaštiti luster.
  Emphasis on with a blanket
• Luster zaštiti ćebetom.
  Emphasis on the chandelier

All of these can be grammatical, but Zaštiti luster ćebetom is a very natural basic instruction.

Yes, in Serbian luster usually means chandelier, ceiling light, or a hanging light fixture.

It is not the same as the English noun luster, which usually means shine or gloss.

So this is a word learners should treat as a false friend:

• Serbian luster = chandelier / ceiling light
• English luster = shine, gloss

These are two sounds English speakers often ask about.

• ž is like the s in measure or vision
  • so Zaštiti begins roughly like zh
• ć is a soft consonant, somewhat like a very soft ch/t sound, but it is not exactly the English ch
  • you hear it in ćebetom

A rough learner-friendly pronunciation might be:

• Zaštiti ≈ ZHA-shti-ti
• ćebetom ≈ CHYE-beh-tom (very approximate)

But the Serbian ć is softer than English ch.

In this sentence:

• luster = accusative singular
• ćebetom = instrumental singular

Their roles are:

• luster = the thing being protected
• ćebetom = the thing used to protect it

So the sentence structure is basically:

• Verb + direct object + instrument

That pattern is very common in Serbian.

The dictionary form is ćebe, meaning blanket.

It is a neuter noun.

Some forms are:

• nominative singular: ćebe
• genitive singular: ćebeta
• dative singular: ćebetu
• accusative singular: ćebe
• instrumental singular: ćebetom

So ćebetom is just the correctly declined form required by the sentence.

Yes, it is natural and understandable.

It sounds like a practical instruction, for example when moving furniture or protecting something during painting or repairs:

• Zaštiti luster ćebetom. = Protect the chandelier with a blanket.

A Serbian speaker might also say similar things like:

• Pokrij luster ćebetom. = Cover the chandelier with a blanket.
• Zaštiti luster najlonom. = Protect the chandelier with plastic sheeting.

So the sentence is perfectly normal, especially in a task-based or instructional context.