Moje cipele su ovde, a cipele moje sestre su tamo.

Because cipele is a feminine plural noun. In Serbian, possessive words like moj / moja / moje agree with the noun in gender, number, and case.

So here:

• cipela = one shoe
• cipele = shoes

With feminine plural cipele, the correct form is moje:

• moje cipele = my shoes

Even though moja means my with a feminine singular noun, it does not match plural cipele.

Yes, it is the same written form, but it is doing a different job grammatically.

In moje cipele, moje agrees with cipele and means my.

In moje sestre, moje agrees with sestre, which is in the genitive singular, because the phrase means of my sister.

So:

• moje cipele = my shoes
• cipele moje sestre = the shoes of my sister / my sister’s shoes

This is one of those cases where Serbian uses the same form moje in two different grammatical environments.

Because Serbian usually expresses this kind of possession with the genitive case.

• sestra = sister (nominative, the basic dictionary form)
• sestre = of the sister / sister’s (genitive singular here)

So:

• cipele moje sestre literally means the shoes of my sister

This is a very common Serbian pattern:

• kuća mog brata = my brother’s house
• auto moje sestre = my sister’s car

Because the normal Serbian pattern is:

thing possessed + possessor in the genitive

So:

• cipele moje sestre = my sister’s shoes

The English-like order moje sestre cipele is not the normal neutral way to say it.

If Serbian wants to put the possessor directly before the noun, it usually uses a possessive adjective, for example:

• sestrine cipele = sister’s shoes / my sister’s shoes (if the context makes clear whose sister)

But the version in your sentence, cipele moje sestre, is very standard and clear.

Yes, by itself it could be ambiguous.

For example:

• Moje sestre su ovde. = My sisters are here.

But in your sentence, the structure makes it clear that moje sestre means of my sister, because it follows cipele and forms a possession phrase:

• cipele moje sestre = my sister’s shoes

So the sentence structure tells you how to understand it.

Here a is a coordinating conjunction that often means something like:

• and
• while
• whereas
• and on the other hand

In this sentence, it links two contrasting pieces of information:

• Moje cipele su ovde, a cipele moje sestre su tamo.

So a is a very natural choice because the sentence contrasts here and there, my shoes and my sister’s shoes.

It is usually weaker and less adversative than ali (but).

In standard Serbian, the present tense of biti (to be) is normally expressed, so su is needed here.

• su = are (3rd person plural)

So:

• Moje cipele su ovde. = My shoes are here.
• Cipele moje sestre su tamo. = My sister’s shoes are there.

Leaving out su would sound nonstandard in an ordinary sentence like this.

Because su is a clitic, and Serbian clitics usually go in the second position of the clause.

In a neutral sentence, that often means they come after the first whole phrase, not necessarily after the first single word.

So:

• Moje cipele | su | ovde
• Cipele moje sestre | su | tamo

That is the normal, neutral word order here.

Serbian word order is flexible, but the placement of clitics follows its own rules.

Yes. Serbian word order is much more flexible than English word order. You can move parts of the sentence to change emphasis or focus.

For example:

• Ovde su moje cipele, a tamo su cipele moje sestre.

This is still natural, but it emphasizes the locations more strongly.

The original version is a neutral, straightforward way to say it.

Yes.

• ovde = here, near the speaker
• tamo = there, over there, farther away

Serbian also has tu, which often refers to a place near the listener or a place already being pointed out.

So the sentence creates a clear contrast:

• ovde = here
• tamo = over there

That makes the contrast stronger than if tu were used.

It is repeated for clarity.

If you said:

• Moje cipele su ovde, a moje sestre su tamo

that would usually mean:

• My shoes are here, and my sisters are there

So Serbian repeats cipele to make it clear that both halves are talking about shoes.

You can sometimes avoid repetition in other ways, but in this sentence the repetition is simple and natural.

Because Serbian does not have articles like English a and the.

That means Serbian usually relies on:

• context
• word order
• demonstratives like ovaj, taj, onaj
• possessives like moj, tvoj, etc.

So cipele can mean shoes or the shoes, depending on context. In this sentence, the possessives already make the meaning specific:

• moje cipele = my shoes
• cipele moje sestre = my sister’s shoes