Pretplatnik bira mobilnu tarifu.

Pretplatnik is in the nominative singular because it is the subject of the sentence — the person who is doing the action.

In Pretplatnik bira mobilnu tarifu, the subscriber is the one choosing, so Croatian uses the nominative form:

• pretplatnik = subscriber

If it were the object instead, its form might change depending on the sentence.

Because mobilnu tarifu is the direct object of the verb bira.

Croatian changes nouns and adjectives according to case. Here, the verb birati (to choose) takes a direct object in the accusative case.

So:

• nominative: mobilna tarifa
• accusative: mobilnu tarifu

Both the adjective and the noun change because they must agree in:

• gender
• number
• case

So:

• mobilna → mobilnu
• tarifa → tarifu

The dictionary form is tarifa.

In vocabulary lists, Croatian nouns are usually given in the nominative singular, so you would learn it as:

• tarifa = tariff, rate, plan

In this sentence it appears as tarifu because it is in the accusative singular.

Bira is the 3rd person singular present tense of the verb birati.

So the verb forms are like:

• ja biram = I choose
• ti biraš = you choose
• on/ona/ono bira = he/she/it chooses

Here, the subject is pretplatnik (subscriber), which is singular, so Croatian uses bira.

Birati is an imperfective verb, and it is often used when talking about:

• a general action
• a repeated action
• an ongoing process
• the act of choosing, without emphasizing completion

So Pretplatnik bira mobilnu tarifu can sound like:

• the subscriber is choosing a mobile plan
• the subscriber chooses a mobile plan

If you wanted to emphasize the completed choice, Croatian would more likely use a perfective verb such as:

• Pretplatnik izabere mobilnu tarifu
• Pretplatnik odabere mobilnu tarifu

At beginner level, the key idea is:

• birati = choosing / choose in a general or ongoing sense
• izabrati / odabrati = choose and complete the choice

Not exactly in everyday usage.

Although tarifa is related to tariff, in this kind of sentence it usually means something more like:

• plan
• pricing plan
• mobile plan
• rate plan

So a natural English translation is often:

• The subscriber chooses a mobile plan

rather than the more literal:

• The subscriber chooses a mobile tariff

The Croatian wording is still completely normal.

Croatian has no articles, so it does not use words like a, an, or the.

That means Pretplatnik bira mobilnu tarifu could be understood in English as:

• The subscriber chooses a mobile plan
• A subscriber chooses a mobile plan
• sometimes even The subscriber chooses the mobile plan

Which English article you choose depends on the context, not on a separate Croatian word.

Yes. Croatian word order is more flexible than English word order because the case endings show what each word is doing.

The neutral, straightforward order here is:

• Pretplatnik bira mobilnu tarifu.

But other orders are possible, for example:

• Mobilnu tarifu bira pretplatnik.
• Bira pretplatnik mobilnu tarifu.

These alternatives may sound more marked, or they may shift the emphasis.

For a learner, the basic pattern to remember is:

• subject + verb + object

So this sentence is a very standard, natural structure.

• pretplatnik is masculine
• tarifa is feminine
• mobilna / mobilnu is an adjective that agrees with tarifa, so here it is in the feminine singular

That is why the adjective looks the way it does:

• nominative feminine singular: mobilna
• accusative feminine singular: mobilnu

Croatian adjectives always match the noun they describe.

A simple learner-friendly pronunciation guide would be:

PRET-plat-neek BEE-ra mo-BEEL-noo ta-REE-foo

A few useful points:

• r is trilled or tapped
• i is like ee in see
• u is like oo in food
• a is like a in father

Croatian spelling is quite regular, so words are usually pronounced much as they are written.

Yes, it is grammatically correct and natural.

It sounds like the kind of sentence you might see in:

• a telecom website
• a form
• instructions
• a marketing or technical context

In everyday conversation, people might also say something slightly more idiomatic depending on context, such as:

• Pretplatnik bira paket.
• Korisnik bira mobilnu tarifu.

But Pretplatnik bira mobilnu tarifu is perfectly good Croatian.