El operador móvil ofrece la tarifa de datos.

Because operador is a masculine noun in Spanish, so it takes el.

• el operador = the operator / provider
• la operadora can also exist, but it usually refers to:
  • a female operator, or
  • in some contexts, a company viewed with a feminine noun such as la empresa operadora

In this sentence, el operador móvil is the normal way to say the mobile operator/provider.

In Spanish, adjectives usually come after the noun.

So:

• operador móvil = mobile operator
• literally: operator mobile

This is the normal word order in Spanish. English often puts adjectives before the noun, but Spanish usually places them after.

Also, móvil agrees in number with the noun:

• el operador móvil
• los operadores móviles

It actually does agree where necessary, but móvil has the same form for masculine and feminine singular.

So you get:

• el operador móvil
• la compañía móvil

But in the plural it changes:

• los operadores móviles
• las compañías móviles

So móvil does show agreement in number, but not a visible masculine/feminine difference in the singular.

Ofrece is the third person singular of the verb ofrecer in the present indicative.

• ofrecer = to offer
• él / ella / usted ofrece = he/she/it offers

Here the subject is el operador móvil, which is singular, so the verb must also be singular:

• El operador móvil ofrece...

This present tense can mean:

• offers (general fact)
• sometimes is offering (depending on context)

It is mostly regular in this sentence, but there is one spelling change in the yo form:

• yo ofrezco
• tú ofreces
• él/ella ofrece
• nosotros ofrecemos

That zc in ofrezco happens to keep the correct sound. But ofrece itself is straightforward and common.

Both are possible, but they mean slightly different things.

• la tarifa de datos = the data plan/rate
• una tarifa de datos = a data plan/rate

Using la can suggest:

• a specific data tariff already known from context, or
• a general product category in advertising or business language

Spanish often uses the definite article in places where English might choose either the or no article depending on context.

De datos means of data and works like a noun complement.

So:

• tarifa = rate / tariff / plan
• tarifa de datos = data plan / data tariff

This is a very common Spanish structure:

• tarifa de internet
• tarjeta de crédito
• centro de salud

English often turns this into a noun + noun combination, but Spanish usually uses de.

Yes. Both are possible, but they are not always identical in tone.

In Spain:

• tarifa de datos is very common in telecom/commercial language
• plan de datos is also understood, but tarifa often sounds more natural in offers from phone companies

Very roughly:

• tarifa focuses on the rate/price package
• plan focuses more on the service plan

Both may appear, but tarifa de datos fits very well in Spain Spanish.

Because the personal a is generally used with people (and sometimes pets or personified beings), not with things.

Here, la tarifa de datos is a thing, so no a is needed:

• El operador móvil ofrece la tarifa de datos.

Compare:

• Veo al cliente. = I see the customer.
• Veo la tarifa. = I see the tariff/plan.

So the absence of a here is completely normal.

Yes. The basic order here is the standard subject + verb + object:

• El operador móvil ofrece la tarifa de datos.

But Spanish allows more flexibility for emphasis. For example:

• La tarifa de datos la ofrece el operador móvil.

That version emphasizes la tarifa de datos.
Still, the original sentence is the most neutral and natural if you are simply stating a fact.

Móvil is pronounced roughly MOH-beel, with the stress on the first syllable.

The written accent mark tells you where the stress goes:

• mó-vil

Without the accent mark, Spanish spelling rules would make you expect a different stress pattern. So the accent is necessary.

Also note that v in Spanish is not pronounced like a strong English v in many accents; it is usually closer to a soft b/v sound.