U rokovnik ću zabilježiti samo najvažnije datume, a ostalo ću prepisati kasnije iz poruke.

Rokovnik is a planner, datebook, diary, or agenda book—something you write appointments, deadlines, or important dates in.

So u rokovnik means into my planner / in my planner, depending on how the action is being viewed.

This is a very common question, because u can take either the accusative or the locative.

• u + accusative = movement/direction into something
• u + locative = location in something

Here, the speaker is thinking of the act of writing the dates into the planner, so u rokovnik is used.

Compare:

• Pišem u rokovnik. = I am writing in/into the planner.
• Datumi su u rokovniku. = The dates are in the planner.

In practice, with verbs of writing, putting, entering, and recording, Croatian often uses u + accusative when the focus is on adding content into a book, notebook, planner, etc.

This is the future tense in Croatian.

It is formed with:

• the clitic form of htjeti = ću
• the infinitive = zabilježiti

So:

• zabilježiti = to note down / to record
• ću zabilježiti = I will note down / I’ll record

The full form would be:

• ja ću zabilježiti

But Croatian usually drops ja unless it is needed for emphasis.

Because ću is a clitic, and Croatian clitics normally go in the second position of the clause.

In this sentence, the first unit is:

• U rokovnik

So the clitic comes right after that:

• U rokovnik ću zabilježiti...

This is normal Croatian word order.

You could also hear other arrangements in different contexts, but the placement of clitics near the beginning of the clause is a basic rule.

Because datume is the direct object of zabilježiti, so it is in the accusative plural.

The noun is:

• nominative singular: datum
• nominative plural: datumi
• accusative plural: datume

The adjective has to agree with the noun:

• najvažnije datume = the most important dates

So the structure is:

• samo = only
• najvažnije = the most important
• datume = dates

Because it agrees with datume, which is:

• masculine in gender
• plural in number
• accusative case
• animate/inanimate distinction matters in Croatian, but here datumi is inanimate, and its accusative plural is datume

So the adjective takes the matching form:

• najvažniji datumi = the most important dates (nominative plural)
• najvažnije datume = the most important dates (accusative plural)

This change is part of normal adjective agreement.

They are similar, but not the same.

• zabilježiti = to write down, note down, record
• prepisati = to copy out, copy over, transcribe

In this sentence:

• zabilježiti samo najvažnije datume = write down only the most important dates
• ostalo prepisati kasnije iz poruke = copy the rest later from the message

So the idea is:

1. first, quickly note only the key dates
2. later, copy the remaining details from the message

Ostalo means the rest or everything else.

It comes from the adjective/pronoun ostao / ostala / ostalo = remaining, left over, other remaining part.

Here it is used substantively, meaning:

• ostalo = the rest of it

It is in the neuter singular, which is very common in Croatian when referring to an unspecified remainder, a set of other things, or everything else generally.

So:

• a ostalo ću prepisati kasnije = and I’ll copy the rest later

Here a is best understood as and, while, or whereas, depending on context.

Croatian a often links two contrasting or separate parts of a statement:

• first part: I’ll note down only the most important dates
• second part: the rest I’ll copy later

So it is not a strong contradiction like ali = but, but it does mark a contrast between what will be done now and what will be done later.

Because iz means from / out of, and it requires the genitive case.

The noun is:

• nominative: poruka = message
• genitive: poruke

So:

• iz poruke = from the message

This means the speaker will later copy the remaining information from the message.

Yes, literally it is something like out of the message, but in natural English you would usually say:

• from the message

Croatian often uses iz where English simply uses from.

Because Croatian usually does not need subject pronouns when the verb form already shows the person.

For example:

• ću zabilježiti = I will note down
• ću prepisati = I will copy

The I is already understood.

You would add ja only for emphasis, contrast, or clarity:

• Ja ću zabilježiti samo najvažnije datume... = I will write down only the most important dates...

Yes, both are perfective:

• zabilježiti = to note down completely / as a completed act
• prepisati = to copy over completely / as a completed act

That matters because Croatian typically uses perfective verbs in the future when talking about a completed one-time action.

Here the speaker means:

• I will note down the important dates
• I will copy the rest later

These are seen as completed actions, not ongoing processes.

Their imperfective counterparts would be things like:

• bilježiti = to be noting down / to note down repeatedly
• prepisivati = to be copying / to copy repeatedly

Yes, Croatian word order is fairly flexible, but not completely free.

This sentence is natural as:

• U rokovnik ću zabilježiti samo najvažnije datume, a ostalo ću prepisati kasnije iz poruke.

You could also rearrange parts for emphasis, for example:

• Samo najvažnije datume ću zabilježiti u rokovnik...
• Ostalo ću kasnije prepisati iz poruke.

But the original version sounds natural and balanced, especially because it emphasizes where the important dates will be written first.

No, Croatian allows some flexibility here.

• ...ću prepisati kasnije iz poruke
• ...ću kasnije prepisati iz poruke
• ...ću prepisati iz poruke kasnije

All are possible, though they may sound slightly different in emphasis.

The original order is very natural. It puts the focus on the action first, then the time (later), then the source (from the message).

Yes, very common.

The order is:

• samo = only
• najvažnije = most important
• datume = dates

So literally:

• only most-important dates

That is exactly how Croatian normally expresses this idea.