Procena troškova je spremna pre roka popravke.

Because procena is a feminine singular noun, and the adjective has to agree with it.

• procena = estimate, assessment
• spremna = ready

In Serbian, adjectives change form to match the noun’s:

• gender
• number
• case

So here:

• procena → feminine singular
• therefore spremna → feminine singular

Compare:

• Plan je spreman. = The plan is ready. (masculine)
• Procena je spremna. = The estimate is ready. (feminine)
• Pismo je spremno. = The letter is ready. (neuter)

Troškova is genitive plural of trošak (cost, expense).

It appears in the phrase:

• procena troškova = estimate of costs

In Serbian, many nouns are followed by another noun in the genitive to express something like English of.

So:

• procena
  • troškova
• literally: estimate of costs

This is very common:

• kraj dana = end of the day
• cena rada = price of labor/work
• plan popravke = repair plan

Because the preposition pre requires the genitive case.

So:

• dictionary form: rok
• after pre: roka

This is the same pattern as:

• pre sastanka = before the meeting
• pre puta = before the trip
• pre škole = before school

In this sentence:

• pre roka popravke = before the repair deadline

Because popravke depends on roka.

The phrase is:

• rok popravke = deadline of the repair / repair deadline

Here:

• rok = deadline, due date
• popravke = of the repair

So the structure is:

• pre
  • roka (genitive because of the preposition)
• popravke (genitive because it depends on rok: deadline of what?)

A helpful way to see it is:

• rok popravke = repair deadline
• pre roka popravke = before the repair deadline

Here rok means deadline, due date, or time limit.

So rok popravke is not just repair time in a general sense. It more specifically means:

• the deadline for the repair
• the scheduled completion time for the repair
• the due date connected with the repair

Depending on context, English might translate it as:

• before the repair deadline
• before the deadline for the repair
• ahead of the repair deadline

Yes. Grammatically, procena troškova literally means assessment/estimate of costs.

In natural English, though, the best translation is often:

• cost estimate

So both ideas are correct:

• procena = assessment / estimate
• troškova = of costs

But in real-world usage, cost estimate is usually the most natural English equivalent.

Je is the 3rd person singular present form of biti (to be).

The sentence has the structure:

• Procena troškova = subject
• je spremna = is ready
• pre roka popravke = before the repair deadline

So je is the Serbian equivalent of English is here.

Without je, the sentence would be incomplete in standard Serbian.

Yes, Serbian word order is more flexible than English, although the original sentence is the most neutral and straightforward.

Neutral order:

• Procena troškova je spremna pre roka popravke.

Other possible orders might be used for emphasis, for example:

• Pre roka popravke procena troškova je spremna.
• Spremna je procena troškova pre roka popravke.

These are grammatically possible, but they may sound more marked or stylistically driven. For a learner, the original version is the safest and most natural default.

You could, but it would mean something slightly different.

• procena troškova = estimate of costs / cost estimate
• procena troška = estimate of a cost / estimate of one specific expense

In many practical contexts, especially business or repair contexts, procena troškova is the normal phrase because there are usually multiple costs involved.

So if you mean a general cost estimate, procena troškova is the better choice.

Spremna is correct and natural, but Serbian can also use other words depending on nuance.

For example:

• Procena troškova je spremna. = The cost estimate is ready.
• Procena troškova je gotova. = The cost estimate is finished/done.

The difference is small in many contexts:

• spremna emphasizes that it is ready for use/presentation
• gotova emphasizes that it is completed

In many real situations, both could work.

You can tell from the form and from agreement.

• procena = singular
• procene = plural or another case form, depending on context

The adjective helps confirm it:

• spremna = feminine singular

If it were plural, you would expect something like:

• Procene troškova su spremne. = The cost estimates are ready.

So in your sentence, both the noun and the adjective clearly point to singular.

A simple breakdown is:

• Procena troškova = noun phrase / subject
• je spremna = verb + predicate adjective
• pre roka popravke = prepositional phrase expressing time

So literally:

• Estimate of costs is ready before deadline of repair.

Natural English:

• The cost estimate is ready before the repair deadline.

This is a good example of how Serbian often uses:

• genitive after nouns for of
• genitive after certain prepositions like pre