Pozajmiće primerak pod uslovom da nema zakasninu.

Pozajmiće is the 3rd person singular future tense of pozajmiti.

• pozajmiti = to borrow / to lend, depending on context
• pozajmiće = he/she/it will borrow or he/she/it will lend

In this sentence, the exact English choice depends on the meaning you were given, but grammatically it is simply future tense.

Serbian often drops subject pronouns when they are not needed.

The ending in pozajmiće already tells you it is 3rd person singular, so Serbian does not need to say on or ona unless the speaker wants emphasis or contrast.

So:

• Pozajmiće primerak. = He/She will borrow/lend a copy.
• On će pozajmiti primerak. = also possible, but more explicit or emphatic

This is very normal in Serbian.

Primerak usually means a copy, an экземпляр / individual copy, or a specimen/example, depending on context.

In a library or book-related context, primerak usually means:

• a copy of a book
• a copy of an item

Here it is the direct object of the verb, so it appears in the form primerak.

Because it is the direct object of pozajmiće.

The noun primerak is masculine inanimate. In the singular, masculine inanimate nouns usually have the same form in nominative and accusative, so:

• nominative: primerak
• accusative: primerak

That is why the form does not change here.

Pod uslovom da means provided that, on condition that, or as long as.

It is a fairly standard and somewhat formal expression. You can think of it as a fixed phrase introducing a condition.

Examples:

• Doći ću pod uslovom da imam vremena.
  = I’ll come provided that I have time.
• Pozajmiće primerak pod uslovom da nema zakasninu.
  = He/She will borrow/lend a copy provided that...

A simpler alternative in everyday speech is often ako = if.

Because in Serbian, after expressions like pod uslovom da, the subordinate clause commonly uses the present tense to refer to a future condition.

So even though the main clause is future:

• Pozajmiće... = will borrow/lend...

the condition is expressed with present:

• da nema... = literally that he/she does not have...

This works like English provided that he/she has no..., where English also does not necessarily use will in the condition clause.

So the structure is normal Serbian:

• main clause in future
• conditional subordinate clause in present

Here nema means does not have.

It comes from the verb imati = to have:

• ima = has
• nema = does not have

So da nema zakasninu means that he/she does not have an overdue fine/fee.

This is different from another common use of nema, which can mean there is no / there are no. Context tells you which meaning is intended.

Because in this sentence, zakasninu is the direct object of the verb nema in the sense does not have.

So the hidden subject is something like:

• on/ona nema zakasninu = he/she does not have an overdue fine

That requires the accusative singular:

• nominative: zakasnina
• accusative: zakasninu

By contrast, if you said nema zakasnine, that would usually be understood more like there is no overdue fine, where zakasnine is genitive.

So the difference is:

• nema zakasninu = he/she doesn’t have an overdue fine
• nema zakasnine = there is no overdue fine

That is an important distinction.

Zakasnina means an overdue fee, late fee, or fine for being late with returning something, especially in a library context.

So if the sentence is about borrowing a library copy, zakasnina is the money owed because something was returned late.

Yes, in many situations you could say:

• Pozajmiće primerak ako nema zakasninu.

That means roughly the same thing: He/She will borrow/lend a copy if he/she has no overdue fine.

The difference is mostly in tone:

• ako = more everyday, simpler
• pod uslovom da = more formal, more explicit, more like provided that

No, Serbian word order is relatively flexible.

The original order is natural and neutral:

• Pozajmiće primerak pod uslovom da nema zakasninu.

But you could also move the conditional part forward:

• Pod uslovom da nema zakasninu, pozajmiće primerak.

Both are grammatical. The difference is mainly about focus and style, not basic meaning.

Yes, that can confuse learners.

In actual usage, pozajmiti may mean either borrow or lend, and context usually makes it clear.

For example:

• Pozajmio sam knjigu od Marka.
  = I borrowed a book from Marko.

• Pozajmio sam Marku knjigu.
  = I lent Marko a book.

So the surrounding words tell you the direction of the action. If your translation already gives the intended meaning, follow that meaning for this sentence.