Mobilni podaci ne rade bez SIM kartice.

In Serbian, podaci is the plural of podatak (a piece of data / a datum / a data item).

So:

• podatak = one item of data
• podaci = data

Serbian normally treats data as a plural noun, so mobilni podaci literally means mobile data but grammatically behaves like mobile data items.

That is why the verb is also plural:

• Mobilni podaci ne rade.
• not Mobilni podaci ne radi.

This is one of those places where Serbian grammar does not match modern everyday English usage.

Because the subject, mobilni podaci, is plural.

• radi = works for singular subjects
• rade = work for plural subjects

Compare:

• Telefon ne radi. = The phone doesn’t work.
• Mobilni podaci ne rade. = Mobile data doesn’t work / Mobile data aren’t working.

Even though English often says data doesn’t work in the singular, Serbian follows the grammar of podaci as a plural noun, so the verb must be plural too.

Yes. Very commonly.

In Serbian, raditi does not only mean to do work. It can also mean:

• to function
• to operate
• to work

So ne rade here means do not work / are not functioning.

Very common examples:

• Auto ne radi. = The car isn’t working.
• Internet ne radi. = The internet isn’t working.
• Aplikacija ne radi. = The app isn’t working.

So this sentence sounds natural.

Because the preposition bez (without) requires the genitive case.

The basic form is:

• SIM kartica = SIM card

After bez, it changes to genitive singular:

• bez SIM kartice = without a SIM card

So the pattern is:

• kartica → nominative singular
• kartice → genitive singular

This is one of the most important case patterns to learn:

• bez telefona = without a phone
• bez interneta = without internet
• bez SIM kartice = without a SIM card

Because adjectives in Serbian must agree with the noun in gender, number, and case.

Here the noun is podaci, which is:

• masculine
• plural
• nominative

So the adjective must also be:

• masculine plural nominative

That gives:

• mobilni podaci

Compare:

• mobilni telefon = masculine singular
• mobilna mreža = feminine singular
• mobilni podaci = masculine plural

Serbian usually forms negation by putting ne before the verb.

So:

• rade = they work
• ne rade = they do not work

This is the normal pattern:

• radi → ne radi
• mogu → ne mogu
• imam → nemam (this one is irregular and merges into one word)

In your sentence, ne rade is just the regular negative form of the present tense.

In this phrase, only kartica changes.

• SIM stays the same
• kartica changes according to case

So:

• SIM kartica = nominative
• bez SIM kartice = genitive after bez

This is very common with abbreviations and foreign-looking elements in Serbian: the abbreviation often stays unchanged, while the ordinary Serbian noun declines.

Yes, you could, and it would sound natural in many situations.

The difference is mainly one of wording:

• mobilni podaci = mobile data
• mobilni internet = mobile internet

In everyday speech, people may use either depending on context.
If you are talking specifically about the phone’s data connection, mobilni podaci is very common and precise.

Serbian does not have articles like English a/an/the.

So:

• SIM kartice here can mean a SIM card or the SIM card, depending on context.
• Mobilni podaci can mean mobile data, the mobile data, or mobile-data service, depending on the situation.

You understand definiteness from context rather than from an article.

Yes. Serbian word order is more flexible than English word order.

The given sentence:

• Mobilni podaci ne rade bez SIM kartice.

is a normal, neutral way to say it.

But you could also say:

• Bez SIM kartice mobilni podaci ne rade.

This puts more emphasis on without a SIM card.

The meaning stays basically the same because the case endings help show the relationships between words.

Yes, it would, but it sounds a bit more formal or technical.

Compare:

• Mobilni podaci ne rade. = natural, everyday
• Mobilni podaci ne funkcionišu. = more formal, more like are not functioning

In ordinary speech, ne rade is usually the most natural choice.

A simple approximate pronunciation for an English speaker is:

MO-beel-nee POH-da-tsee neh RAH-deh bez seem KAR-tee-tseh

A few notes:

• j in Serbian sounds like English y
• c sounds like ts
• č / ć are different Serbian sounds, but here you only have c in kartice
• stress is not marked in normal writing, so learners usually just imitate native pronunciation

Word by word:

• mobilni ≈ MO-beel-nee
• podaci ≈ POH-da-tsee
• ne rade ≈ neh RAH-deh
• bez ≈ bez
• SIM kartice ≈ seem KAR-tee-tseh

Here are the basic forms:

• mobilni → dictionary form of the adjective is mobilan or listed in forms like mobilni depending on the dictionary entry
• podaci → basic singular noun is podatak
• ne rade → verb is raditi
• bez → preposition meaning without
• kartice → basic noun form is kartica
• SIM → abbreviation, unchanged

So if you were looking things up, the most useful entries would be:

• podatak
• raditi
• bez
• kartica

Yes. It sounds natural and idiomatic.

A Serbian speaker would readily understand it as meaning that mobile data cannot function unless there is a SIM card in the device.

It is short, everyday, and grammatically normal:

• plural noun podaci
• plural verb rade
• correct genitive after bez

So this is a good real-life model sentence.