Javnobilježnički akt je valjan.

Because Croatian often forms a single adjective from a noun phrase.

Here, the base expression is javni bilježnik = notary public.
From that, Croatian makes the adjective javnobilježnički, meaning notarial or related to a notary public.

So:

• javni bilježnik = a notary public
• javnobilježnički akt = a notarial act/document

This is very normal in Croatian, especially in formal and legal language.

Not exactly.

In this sentence, akt means something like:

• document
• deed
• legal instrument
• formal act

It does not mean an action or performance in the everyday English sense of act.

So in legal Croatian, akt often refers to an official written document.

Because Croatian has no articles.

English says the notarial act or a notarial act, but Croatian does not use words like the or a/an.
Whether something is definite or indefinite is usually understood from context.

So Javnobilježnički akt je valjan can mean:

• The notarial act is valid
• A notarial act is valid

The exact interpretation depends on the situation.

Here is the breakdown:

• javnobilježnički = adjective, describing akt
• akt = noun, the subject
• je = is, 3rd person singular present of biti = to be
• valjan = adjective meaning valid, used as the predicate adjective

So the structure is:

[adjective + noun] + je + [predicate adjective]

In other words:

• Javnobilježnički akt = the notarial act/document
• je valjan = is valid

Because it agrees with akt.

Akt is:

• masculine
• singular
• nominative

So the adjective must match it:

• masculine singular: valjan
• feminine singular: valjana
• neuter singular: valjano
• masculine plural: valjani

Examples:

• Isprava je valjana. = The document is valid.
• Rješenje je valjano. = The decision/solution is valid.
• Akti su valjani. = The acts/documents are valid.

Both javnobilježnički akt and valjan are in the nominative.

Why?

• akt is the subject, so nominative is expected.
• after biti in a sentence like this, the predicate adjective also appears in the nominative.

So:

• javnobilježnički akt = nominative singular masculine
• valjan = nominative singular masculine

This is a standard pattern in Croatian with to be + adjective.

Yes, in a normal full sentence it is.

Je is the present-tense form of biti = to be, and Croatian normally keeps it in sentences like this:

• Akt je valjan. = The act is valid.

If you remove it, the sentence sounds incomplete in standard prose.

You may sometimes see omission in:

• headlines
• notes
• very compressed legal or journalistic style

But in ordinary correct sentence structure, je should be there.

Yes, Croatian word order is more flexible than English, but not every change sounds equally natural.

The neutral order here is:

• Javnobilježnički akt je valjan.

You could also hear:

• Javnobilježnički akt valjan je.

That is possible, but it sounds more marked, formal, or stylistically emphatic.

If you change the order too much, the sentence may become awkward or shift the emphasis.

So for a learner, the safest normal version is:

Javnobilježnički akt je valjan.

Because attributive adjectives in Croatian usually come before the noun.

So:

• javnobilježnički akt = notarial act/document
• valjan akt = valid act/document

This is the normal position for adjectives that directly modify a noun.

In this sentence:

• javnobilježnički is an attributive adjective before the noun
• valjan is a predicate adjective after je

That is why the sentence has both patterns:

• javnobilježnički akt
• je valjan

They are similar, but not identical.

• valjan usually means valid, legally sound, acceptable
• važeći usually means in force, currently applicable, effective

In legal contexts, this difference matters.

For example:

• ugovor je valjan = the contract is valid
• zakon je važeći = the law is in force / currently applicable

So in Javnobilježnički akt je valjan, valjan is the natural choice if you mean the document is legally valid.

You make it negative by changing je to nije:

• Javnobilježnički akt nije valjan.

That means:

• The notarial act is not valid.

This is the normal Croatian negation of is.

A very common way is:

• Je li javnobilježnički akt valjan?

That means:

• Is the notarial act valid?

The pattern Je li ...? is a standard way to form yes/no questions in Croatian.

You may also hear a more conversational pattern in speech, but Je li ...? is the safest standard form for learners.

A rough English-friendly guide would be:

• j sounds like English y
• ž sounds like the s in measure
• lj is a soft sound somewhat like lli in some pronunciations of million

So approximately:

• javnobilježnički ≈ YAHV-no-bee-LYEZH-nich-kee
• valjan ≈ VAHL-yan

This is only an approximation, but it helps with the main sounds:

• j = y
• ž = the sound in measure
• lj = a soft ly-type sound

It would be:

• Javnobilježnički akti su valjani.

Changes:

• akt → akti = acts/documents
• je → su = are
• valjan → valjani = valid, masculine plural

So the agreement changes across the sentence, just as it would in English:

• The notarial act is valid.
• The notarial acts are valid.