Replika itu bukan barang antik.

In Indonesian, demonstratives like ini and itu usually come after the noun they modify.

So:

• replika itu = that replica
• barang antik itu = that antique item / that antique object

This is different from English, where this/that usually comes before the noun.

In your sentence, replika itu means that replica.

Because bukan is the normal negator for nouns and noun phrases.

Here, barang antik is a noun phrase, so:

• bukan barang antik = not an antique item

A useful rule is:

• bukan negates nouns and noun phrases
• tidak negates verbs, adjectives, and some other non-noun elements

Examples:

• Ini bukan mobil. = This is not a car.
• Mobil itu tidak mahal. = That car is not expensive.
• Saya tidak tahu. = I do not know.

So Replika itu bukan barang antik is correct because the thing being denied is a noun phrase: barang antik.

Indonesian often leaves out the verb to be in simple statements like this.

So:

• Replika itu bukan barang antik. literally looks like:
• That replica not antique item.

But naturally it means:

• That replica is not an antique.

This is very common in Indonesian. You do not usually need a separate word for is/am/are in basic present-tense sentences.

Barang means thing, item, goods, object, depending on context.

Antik means antique.

Together, barang antik means:

• an antique item
• an antique object
• an antique

So the phrase is very natural Indonesian. It refers to an object that is antique, not just something that looks old.

Because in Indonesian, adjectives usually come after the noun.

So:

• barang antik = antique item
• rumah besar = big house
• buku baru = new book

This is the normal pattern:

• noun + adjective

So antik barang would sound wrong in standard Indonesian.

Yes, replika is basically a loanword and means replica: a copy or reproduction of something.

For example, a museum might display a replika of an ancient statue rather than the original.

So in this sentence, replika itu refers to something that looks like an older or original object, but is actually a copy.

Indonesian does not normally use articles the way English does.

English requires words like:

• a
• an
• the

Indonesian usually does not.

So:

• barang antik can mean an antique item, the antique item, or just antique goods/items, depending on context.

In your sentence, context tells us the most natural English translation is an antique or an antique item.

You usually would not say it that way in normal Indonesian.

Replika itu is a complete noun phrase meaning that replica. Without itu, replika by itself sounds more general, like a replica / replicas / replica as a category, depending on context.

So:

• Replika itu bukan barang antik. = That replica is not an antique.
• Replika bukan barang antik. = A replica is not an antique / Replicas are not antiques.

The second one sounds more general and less tied to one specific object.

Yes, but that would change the meaning.

Compare:

• Replika itu bukan barang antik.
  = That replica is not an antique.

• Replika bukan barang antik itu.
  = The replica is not that antique item.

So the position of itu matters. It attaches to the noun phrase right before it.

By itself, it does not clearly show singular or plural. Indonesian nouns often do not change form for number.

So barang antik could refer to:

• an antique item
• antique items

The context usually tells you which one is meant.

In this sentence, because replika itu refers to one specific thing, the natural interpretation is singular:

• not an antique item
• not an antique

You could add emphasis words such as sama sekali or stress bukan in speech.

For example:

• Replika itu bukan barang antik sama sekali.
  = That replica is not an antique at all.

You could also say:

• Replika itu memang bukan barang antik.
  = That replica really is not an antique.

These do not change the basic grammar; they just add emphasis.

A simple pronunciation guide is:

• replika ≈ reh-plee-kah
• itu ≈ ee-too
• bukan ≈ boo-kahn
• barang ≈ bah-rahng
• antik ≈ ahn-teek

A rough full reading:

• reh-plee-kah ee-too boo-kahn bah-rahng ahn-teek

Indonesian pronunciation is generally quite regular, and each vowel is usually pronounced clearly.