Operacija može promijeniti sudbinu.

Because sudbinu is in the accusative singular, not the nominative.

• sudbina = nominative singular, the dictionary form
• sudbinu = accusative singular

In this sentence, sudbinu is the direct object of promijeniti (to change), so Croatian uses the accusative:

• Sudbina se mijenja. = Fate is changing.
• Operacija može promijeniti sudbinu. = The operation can change fate.

Since sudbina is a feminine noun ending in -a, its accusative singular typically changes to -u.

Because it agrees with the subject operacija, which is singular.

• operacija = operation, singular
• može = can / is able to, 3rd person singular

So:

• Operacija može... = The operation can...

If the subject were plural, the verb would also be plural:

• Operacije mogu promijeniti sudbinu. = Operations can change fate.

Može is the 3rd person singular present tense of the verb moći (to be able to / can).

A few useful forms of moći are:

• ja mogu = I can
• ti možeš = you can
• on/ona/ono može = he/she/it can
• mi možemo = we can
• vi možete = you can
• oni/one/ona mogu = they can

In your sentence, operacija is singular, so Croatian uses može.

Because after the modal verb može, Croatian normally uses an infinitive.

So the structure is:

• može + infinitive
• can + base verb

Examples:

• Može pomoći. = It can help.
• Može uspjeti. = It can succeed.
• Može promijeniti sudbinu. = It can change fate.

This is very similar to English, although English uses the bare verb form after can, while Croatian uses the infinitive.

This is about aspect, which is very important in Croatian.

• promijeniti = perfective
• mijenjati = imperfective

Very roughly:

• promijeniti focuses on a completed change or the result of changing
• mijenjati focuses on the process, repetition, or ongoing action

In Operacija može promijeniti sudbinu, the idea is that the operation can bring about a change in fate. That is a result, so the perfective verb promijeniti is natural here.

Compare:

• Operacija može promijeniti sudbinu.
  = the operation can change fate, bring about a new outcome

• Operacija može mijenjati živote.
  = the operation can be changing / affect repeatedly / change in an ongoing sense lives

In this sentence, promijeniti is the more natural choice.

Yes, promijeniti is the standard spelling.

The stem here is related to promjena (change) and mijenjati (to change), and in standard Croatian the infinitive is:

• promijeniti

Not:

• promjeniti ✘

This is a very common learner mistake, and even native speakers sometimes misspell it informally, but promijeniti is the correct standard form.

Operacija is a feminine noun.

You can usually recognize many feminine Croatian nouns because they end in -a, though there are exceptions in the language as a whole.

It matters because the verb and other words may agree with the noun when necessary. In this sentence:

• operacija = feminine singular
• može = singular verb form

The present tense verb does not show gender in the same way adjectives or past-tense forms do, but the noun’s gender is still part of its grammar.

For example, in the past tense you would see gender more clearly:

• Operacija je promijenila sudbinu. = The operation changed fate.

Here promijenila shows feminine singular agreement.

Yes. Croatian word order is more flexible than English word order.

The neutral, straightforward order here is:

• Operacija može promijeniti sudbinu.

But other orders are possible, depending on emphasis:

• Sudbinu može promijeniti operacija.
  Emphasis on fate
• Operacija sudbinu može promijeniti.
  More marked; can sound literary or emphatic

Even though Croatian allows this flexibility, not every order sounds equally neutral. For a learner, subject + verb + object is the safest default.

Because Croatian does not have articles like the or a/an.

So:

• operacija can mean operation, an operation, or the operation
• sudbinu can mean fate, a fate, or the fate, depending on context

Croatian expresses definiteness through context rather than articles.

So Operacija može promijeniti sudbinu could be understood in English in slightly different ways depending on context:

• An operation can change fate.
• The operation can change fate.

The Croatian sentence itself does not need an article.

A simple approximate pronunciation is:

opeh-RAH-tsee-ya MOH-zhe proh-MYEH-nee-tee SOOD-bee-noo

A few key points:

• č sounds like ch in church
• ć is a softer sound, though many learners do not hear the difference at first
• ž sounds like the s in measure
• j sounds like English y
• ije in promijeniti is pronounced roughly yeh

Word by word:

• Operacija = o-pe-ra-ci-ja
• može = mo-zhe
• promijeniti = pro-mi-je-ni-ti
• sudbinu = sud-bi-nu

Stress in Croatian is not usually marked in normal writing, so learners often pick it up by listening.

Not only, but in many everyday contexts that is the most likely meaning.

Operacija can mean:

• a surgical operation
• an operation in a broader sense, such as military or strategic contexts

Without more context, many people would first think of a medical operation. But the word itself is broader, just like English operation can be.

So the sentence could sound dramatic in a medical context:

• A surgery can change fate.

But grammatically, the sentence itself does not force only one interpretation.

In standard Croatian, the usual form is:

• Operacija može promijeniti sudbinu.

The pattern može da + present tense is common in some other South Slavic varieties, especially Serbian, but it is not the normal standard Croatian choice here.

So for Croatian, you should prefer:

• može promijeniti ✔

rather than:

• može da promijeni ✘ or non-standard for Croatian

For a learner of Croatian, sticking with modal + infinitive is the best approach.