Ovo je ugovor na određeno vrijeme.

Ovo means this.

In Croatian, both ovo and to can point to something, but they are not used in exactly the same way:

• ovo = this (something near the speaker)
• to = that or sometimes it/that depending on context

In Ovo je ugovor na određeno vrijeme, ovo is natural if you are showing or referring to a specific document in front of you: This is a fixed-term contract.

Also, ovo is the neuter form, which is often used when pointing to an object in a general way, especially with this is ... type sentences.

Croatian has a strong tendency for short unstressed words, called clitics, to appear in second position in the sentence.

Here:

• Ovo = first element
• je = short form of to be, so it goes after the first element

So:

• Ovo je ugovor ... = natural
• Ovo ugovor je ... = wrong

This second-position rule is very common in Croatian and is something learners notice a lot.

Ugovor is in the nominative singular here.

That is because it is the predicate noun after je in a sentence meaning This is a contract.

Structure:

• Ovo = this
• je = is
• ugovor = contract

So ugovor is the basic dictionary form.

Croatian does not have articles like English a/an and the.

So ugovor can mean:

• a contract
• the contract

The exact meaning depends on context.

In this sentence, English might translate it as either:

• This is a fixed-term contract
• This is the fixed-term contract

Usually context tells you which one is meant.

Literally, it means something like for a determined time or for a specific period of time.

In natural English, the whole phrase usually means:

• for a fixed term
• for a limited period
• temporary in contract language

So:

• ugovor na određeno vrijeme = fixed-term contract

This is a standard Croatian expression, especially in job and legal contexts.

Because određeno agrees with vrijeme, and vrijeme is a neuter noun.

Croatian adjectives must agree with the noun they describe in:

• gender
• number
• case

Here:

• vrijeme = neuter singular
• so the adjective must also be neuter singular: određeno

Compare:

• određeni ugovor = a specific contract / the specified contract
  because ugovor is masculine
• određeno vrijeme = a specific/fixed period of time
  because vrijeme is neuter

Here vrijeme is in the accusative singular, although it looks the same as the nominative.

The preposition na can take different cases depending on meaning. In this expression, na određeno vrijeme, it is part of a fixed phrase meaning for a fixed period.

With neuter nouns like vrijeme, nominative and accusative singular are often identical in form, so you do not see a change.

So grammatically:

• na
  • accusative
• određeno vrijeme

Yes, very much so.

It is a standard expression used in employment and legal language:

• ugovor na određeno vrijeme = fixed-term contract
• rad na određeno vrijeme = fixed-term employment / temporary employment

The common opposite is:

• ugovor na neodređeno vrijeme = permanent contract / contract for an indefinite period

So this is a phrase worth learning as a whole, not just word by word.

Yes. In fact, that is often even more precise.

• ugovor = contract
• ugovor o radu = employment contract
• ugovor o radu na određeno vrijeme = fixed-term employment contract

Your original sentence is perfectly natural, but in formal employment contexts Croatian often uses the fuller version ugovor o radu.

Yes, Croatian word order is fairly flexible, but not every version sounds equally natural.

The most neutral sentence is:

• Ovo je ugovor na određeno vrijeme.

You could also hear:

• To je ugovor na određeno vrijeme.

But the original order is the most straightforward if you are identifying something in front of you.

Because je is a clitic, it still usually stays in second position relative to the first sentence element.

A rough pronunciation guide:

• određeno ≈ od-re-jye-no
• vrijeme ≈ vree-ye-me

A few useful notes:

• đ is a soft sound, somewhat like the j in judge, but softer
• ij / je combinations in words like vrijeme can be tricky for English speakers
• vrijeme is said in three syllables: vri-je-me

If you say it slowly as vri-ye-me, that will help a lot at first.

A very common opposite is:

• Ovo je ugovor na neodređeno vrijeme.

That means:

• This is a permanent contract
• literally, This is a contract for an indefinite period

This contrast is extremely important in Croatian employment vocabulary:

• na određeno vrijeme = fixed-term
• na neodređeno vrijeme = indefinite / permanent

So these two expressions are often learned together.