Ona opet čita tu knjigu.

Yes. In Croatian, the verb ending already shows the subject, so čita by itself can mean she reads / she is reading.

Ona is often included for one of these reasons:

• to emphasize the subject: She is reading it again
• to contrast with someone else: He isn’t, but she is
• to make the subject clearer in context

So:

• Čita tu knjigu. = She is reading that book / She reads that book.
• Ona čita tu knjigu. = same basic meaning, but with more focus on she

Čita is the present tense, 3rd person singular of the verb čitati (to read).

So:

• ja čitam = I read / I am reading
• ti čitaš = you read / you are reading
• on/ona/ono čita = he/she/it reads / is reading

Croatian present tense can often cover both English ideas:

• she reads
• she is reading

The exact meaning depends on context.

It can mean either, depending on context.

In Croatian, the present tense often does the work of both:

• habitual: She reads that book again
• ongoing right now: She is reading that book again

Because the sentence contains opet (again), many learners will naturally understand it as:

• She is reading that book again

  But in the right context it could also mean:

• She reads that book again
  for example, if talking about repeated behavior

Because knjigu is the accusative singular form, not the nominative.

The verb čitati normally takes a direct object—the thing being read. In Croatian, a direct object usually goes in the accusative case.

So:

• ta knjiga = that book as a subject form (nominative)
• tu knjigu = that book as an object form (accusative)

Here, book is the thing being read, so Croatian uses the accusative:

• Ona čita tu knjigu.

Because the demonstrative adjective has to match the noun’s case, gender, and number.

The noun knjiga is:

• feminine
• singular

In the accusative singular feminine, ta becomes tu.

So:

• ta knjiga = that book (nominative)
• tu knjigu = that book (accusative)

This matching is very important in Croatian. The demonstrative and the noun change together.

For the same reason: knjigu is the accusative singular of knjiga.

Since book is the direct object of čitati, Croatian uses the accusative:

• knjiga = book (nominative, dictionary form)
• knjigu = book (accusative singular)

This is a very common pattern with many feminine nouns ending in -a:

• žena → ženu
• kuća → kuću
• knjiga → knjigu

Opet means again.

In this sentence, it shows that the action is repeated:

• Ona opet čita tu knjigu. = She is reading that book again.

Depending on context, opet can suggest things like:

• repetition: she has returned to that action
• sometimes mild annoyance or surprise: She’s reading that book again?

The tone depends on how it is said and what comes before it.

Yes. Croatian word order is fairly flexible, and opet can move around, though the emphasis may change slightly.

For example:

• Ona opet čita tu knjigu.
• Opet ona čita tu knjigu.
• Ona čita opet tu knjigu.

These all relate to again, but they do not sound equally neutral.

The most natural neutral version here is:

• Ona opet čita tu knjigu.

Changing the position can add emphasis, for example on again or on she.

No, not as fixed as in English.

Because Croatian uses case endings, word order is more flexible. The endings tell you what role a word plays, so the sentence can often be rearranged.

Still, word order affects:

• emphasis
• information structure
• what sounds most natural in context

A neutral order here is:

• Ona opet čita tu knjigu.

Other orders are possible, such as:

• Tu knjigu ona opet čita.
• Opet čita tu knjigu.

These are grammatical, but they put focus on different parts of the sentence.

Yes, absolutely.

That would be very natural Croatian:

• Opet čita tu knjigu.

Since čita already shows he/she/it, the pronoun is often omitted unless needed for emphasis or clarity.

So both are correct:

• Ona opet čita tu knjigu.
• Opet čita tu knjigu.

The version with ona gives a little extra focus to she.

The basic form is čitati (to read), and it is imperfective.

That matters because imperfective verbs are commonly used for:

• ongoing actions
• repeated actions
• habitual actions
• general processes

That fits well with opet (again) and with the present tense.

Croatian often has aspect pairs, and čitati is the imperfective partner used for reading as a process. In many contexts, that is exactly the form you want for is reading or reads.

In most beginner contexts, tu knjigu is best understood as that book.

The demonstrative taj / ta / to often points to something relatively near the listener or already known in the conversation. In practice, English translations may vary depending on context:

• that book
• sometimes this book
• sometimes even the book, if the reference is already clear

But if you are learning the core meaning, that book is the safest choice here.

A rough guide:

• čita sounds approximately like CHEE-ta
• knjigu is roughly KNYEE-goo

A few important sounds:

• č is like ch in church, but often a bit firmer
• nj is like the ny sound in canyon
• g is always a hard g, as in go

So the whole sentence is approximately:

• Ona opet čita tu knjigu
• OH-na OH-pet CHEE-ta too KNYEE-goo

This is only an approximation, but it helps as a starting point.