Traficul de date poate avea costuri suplimentare în roaming.

Because Romanian often adds the definite article to the end of the noun.

• trafic = traffic
• traficul = the traffic

So Traficul de date means the data traffic or, more naturally in context, data usage / data traffic.

This attached article is very common in Romanian:

• telefon → telefonul = the phone
• cost → costul = the cost
• trafic → traficul = the traffic

de links the two nouns and works a bit like of in English.

• traficul de date = traffic of data
• natural English equivalent: data traffic or data usage

This structure is very common in Romanian:

• carte de istorie = history book
• număr de telefon = phone number
• trafic de internet = internet traffic

So de date tells you what kind of traffic it is.

Yes. In Romanian, date means data.

It is the plural of dată in some uses, but in modern practical language date is very often used as a mass/plural-style noun meaning data, especially in tech, telecom, and computing.

So in this sentence, date has nothing to do with calendar dates.

Because poate is the 3rd person singular of a putea = to be able to / can / may, and avea is the infinitive to have.

So the pattern is:

• poate
  • infinitive

Examples:

• poate avea = can have / may have
• poate costa = can cost / may cost
• poate fi = can be / may be

This is similar to English modal-style meaning, although Romanian uses the full infinitive after poate.

It can suggest either, depending on context.

In a warning like this, poate avea usually means something like:

• may have
• can involve
• can incur

So the sense is not about ability in a physical sense. It is more about possibility or potential consequence.

That is why this kind of sentence is common in official notices and phone-company messages.

Romanian often uses simpler, more general verbs where English may prefer a more specific one.

So:

• poate avea costuri suplimentare literally = can/may have additional costs
• natural English in context = may incur additional charges

Romanian a avea is extremely common and flexible, much like to have in English.

Because Romanian commonly uses the plural when talking about charges, costs, fees, expenses in a general sense.

• cost = one cost
• costuri = costs / charges

So costuri suplimentare means additional costs/charges.

Also note the adjective agreement:

• cost → suplimentar
• costuri → suplimentare

The adjective changes form to match the noun in number and gender.

Because suplimentare agrees with costuri.

Here is the basic idea:

• singular masculine/neuter: suplimentar
• plural masculine/neuter: suplimentare

Since costuri is plural, the adjective must also be plural:

• cost suplimentar = additional cost
• costuri suplimentare = additional costs

Romanian adjectives must agree with the noun they describe.

roaming is a widely used borrowing in Romanian telecom language. It is very common to see exactly în roaming in phone-company messages.

So:

• în roaming = while roaming / in roaming

Romanian does have more explanatory ways to express the idea, but in real-life telecom usage the English-based term roaming is standard and very natural.

Because Romanian uses în for many expressions meaning in, while in, or under the condition of something.

Here, în roaming means something like:

• while in roaming
• when using roaming
• in roaming mode/status

So în introduces the situation in which the extra charges may apply.

This word order is the most natural and neutral for an informational warning.

• Traficul de date = subject
• poate avea = verb phrase
• costuri suplimentare = object/complement
• în roaming = context/situation

Romanian word order is somewhat flexible, but this order sounds standard, clear, and formal. It is exactly the kind of structure you would expect in a telecom or legal notice.

Yes, it is fairly formal and informational.

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

• a mobile operator’s website
• contract terms
• an SMS warning
• a settings or billing notice

It is not overly complicated, but it is definitely service-provider language, not casual everyday conversation.

In this context, a Romanian speaker would usually understand it as mobile data usage or internet data traffic.

So although the literal wording is data traffic, the real-world meaning is closer to:

• using mobile data
• mobile internet consumption
• data usage on your phone

That is why this phrase appears so often in telecom contexts.

A helpful approximate pronunciation is:

TRA-fi-kul de DA-te POA-te a-VE-a kos-TURI su-pli-men-TA-re in RO-ming

A few notes:

• tr in Traficul is like English tr
• date is DA-te, not like English date
• poate is roughly POA-te
• avea has three syllables: a-VE-a
• roaming is usually pronounced close to the English-based form, adapted to Romanian speech

If you want to sound natural, keep the stress especially clear on:

• TRAficul
• DAte
• POAte
• costURI
• suplimenTAre
• ROaming