Procena troškova zavisi od dijagnostike.

Because troškova is the genitive plural form of troškovi (costs / expenses).

In procena troškova, Serbian uses a very common pattern:

• noun + genitive
• procena = estimate / assessment
• troškova = of costs

So procena troškova literally means estimate of costs or cost estimate.

If you used troškovi, that would be the nominative plural form, which would not fit after procena in this structure.

Because the verb zavisiti (to depend) normally goes with od + genitive.

So:

• zavisiti od nečega = to depend on something

That means:

• od dijagnostike = on the diagnostics / on the diagnostic process

Here dijagnostike is the genitive singular of dijagnostika.

So the structure is:

• Procena troškova = the cost estimate
• zavisi od dijagnostike = depends on the diagnostics

Usually, yes, od often means from. But in this expression, it is part of the fixed pattern zavisiti od, which means to depend on.

So you should learn this as a set phrase:

• zavisiti od = to depend on

A few examples:

• Sve zavisi od vremena. = Everything depends on the weather.
• Uspeh zavisi od rada. = Success depends on work.

So in this sentence, translating od as from would sound unnatural in English, even though that is one of its basic meanings.

Zavisi is the 3rd person singular present tense of zavisiti (to depend).

Why singular? Because the subject is procena, which is singular:

• procena = estimate
• procena ... zavisi = the estimate depends

So:

• ja zavisim = I depend
• ti zavisiš = you depend
• on/ona/ono zavisi = he/she/it depends

Here the subject is feminine (procena), but in the present tense the 3rd person singular form is the same regardless of gender.

Here it is singular: genitive singular of dijagnostika.

That is important because dijagnostike can look ambiguous to a learner. Depending on context, forms ending in -e can sometimes be plural or singular in Serbian. But in this sentence, the preposition od requires the genitive, and the intended meaning is singular:

• dijagnostika = diagnostics / diagnostic procedure
• od dijagnostike = on the diagnostics / on the diagnostic procedure

So context tells you it is genitive singular, not plural.

This is a very useful distinction.

• dijagnostika = diagnostics, diagnostic procedure, the process of examining/testing
• dijagnoza = diagnosis, the conclusion/result

So:

• od dijagnostike suggests the estimate depends on the diagnostic examination or testing process
• od dijagnoze would suggest it depends on the diagnosis itself

In practical contexts, both might appear, but they are not exactly the same word.

Because Serbian has no articles.

English distinguishes:

• a cost estimate
• the cost estimate

Serbian does not have separate words for a or the. The meaning comes from context.

So Procena troškova zavisi od dijagnostike could mean:

• A cost estimate depends on diagnostics
• The cost estimate depends on the diagnostics
• Cost estimation depends on diagnostics

The exact English version depends on the situation.

Yes, Serbian word order is more flexible than English word order, because case endings show grammatical relationships.

The neutral order here is:

• Procena troškova zavisi od dijagnostike.

But for emphasis, you could also say:

• Od dijagnostike zavisi procena troškova.

That version puts emphasis on od dijagnostike: It is on the diagnostics that the cost estimate depends.

Even though word order can change, the original sentence is the most straightforward and neutral version.

Yes. Serbian nouns often allow a broader, more general meaning depending on context.

Procena troškova can mean:

• the cost estimate
• a cost estimate
• cost assessment
• estimating costs

So the phrase may refer to:

1. one specific estimate, or
2. the general process of estimating costs

You decide from context. Serbian often leaves that kind of distinction unstated unless it needs to be explicit.

The main ones to notice are:

• š = sh as in shoe
• ž = the sound in measure
• c = ts as in cats

So roughly:

• Procena ≈ pro-tse-na
• troškova ≈ trosh-ko-va
• zavisi ≈ za-vi-si
• dijagnostike ≈ di-yag-nos-ti-ke

A rough full pronunciation would be:

pro-TSE-na TROSH-ko-va za-VI-si od di-yag-NOS-ti-ke

That is only an approximation for an English speaker, but it is good enough to get started.