Ovjerena izjava mora biti potpuna.

A word-by-word breakdown is:

• ovjerena = certified, verified, notarized
• izjava = statement, declaration
• mora = must
• biti = to be
• potpuna = complete, full

So the sentence means something like:

• The certified statement must be complete.
• The notarized declaration must be complete.

The exact English wording depends on context.

Because they both agree with izjava, which is:

• feminine
• singular
• nominative

In Croatian, adjectives must match the noun they describe in gender, number, and case.

So:

• izjava = feminine singular nominative
• ovjerena = feminine singular nominative
• potpuna = feminine singular nominative

That is why you see -a on both adjectives.

It is in the nominative singular.

Why?

Because izjava is the subject of the sentence:

• Ovjerena izjava = the certified statement

In Croatian, the subject of a sentence is normally in the nominative.

Because potpuna is an adjective, and Croatian normally uses biti (to be) to link the subject with an adjective.

So:

• izjava mora biti potpuna = the statement must be complete

If you said only izjava mora potpuna, that would be ungrammatical.

Think of it like English:

• must be complete, not just must complete.

No. After biti when an adjective describes the subject, Croatian usually uses the adjective in the same form as the subject.

So:

• izjava = nominative feminine singular
• potpuna = nominative feminine singular

This is similar to saying:

• Kuća je velika = The house is big
• Izjava je potpuna = The statement is complete

The adjective agrees with the subject.

Ovjerena is an adjective-like form derived from the verb ovjeriti (to certify / verify / notarize).

In practice, learners usually treat it as a normal adjective here:

• ovjerena izjava = a certified/notarized statement

It originally comes from a passive idea, roughly a statement that has been certified.

So although it behaves like an adjective in the sentence, it carries the meaning of something that has already been officially verified.

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

The neutral order here is:

• Ovjerena izjava mora biti potpuna.

You may also hear:

• Izjava mora biti ovjerena i potpuna. = The statement must be certified and complete.

But if you only rearrange this exact sentence, the emphasis changes. Croatian often uses word order to highlight information.

For a learner, the safest choice is to keep the standard order:

• Ovjerena izjava mora biti potpuna.

No. Croatian does not use articles like English a and the.

So izjava can mean:

• a statement
• the statement

The context tells you which one is meant.

That is why Ovjerena izjava mora biti potpuna can be translated as either:

• A certified statement must be complete
• The certified statement must be complete

depending on the situation.

They both agree with izjava, but they do different jobs:

• ovjerena directly modifies the noun:
  ovjerena izjava = certified statement
• potpuna is part of the predicate after mora biti:
  mora biti potpuna = must be complete

So one adjective is inside the noun phrase, and the other is part of the main statement about the subject.

Yes. Ovjerena can mean different things depending on context:

• certified
• verified
• notarized
• authenticated

In legal or administrative contexts, notarized is often a very natural translation.

So if the document is being officially validated by an authority or a notary, A notarized statement must be complete may be the best English version.

The adjectives would change to match the gender of the noun.

For example:

• feminine: Ovjerena izjava mora biti potpuna.
• masculine: Ovjeren dokument mora biti potpun.
• neuter: Ovjereno pismo mora biti potpuno.

Notice how the adjective endings change:

• feminine: ovjerena, potpuna
• masculine: ovjeren, potpun
• neuter: ovjereno, potpuno

This is a very important Croatian pattern: adjectives must agree with the noun.