El límite de datos afecta a los datos móviles.

Because límite is a masculine noun in Spanish: el límite.

The ending -e does not tell you the gender reliably. Unlike many nouns ending in -o or -a, nouns ending in -e just have to be learned individually.

So in this sentence:

• el límite = the limit
• los límites = the limits

Because the subject of the sentence is el límite de datos, and the main noun there is límite, which is singular.

• El límite de datos = subject
• afecta = singular verb, matching límite
• a los datos móviles = what is affected

A common English-speaker mistake is to look at datos and think the verb should be plural. But de datos is just extra information describing límite. The head noun is still singular.

Compare:

• El límite de datos afecta...
• Los límites de datos afectan...

Because afectar is normally used as afectar a algo/alguien.

So:

• afecta a los datos móviles
• afecta a la batería
• afecta a los usuarios

This a is part of the normal pattern of the verb here. It is not just the usual personal a, because it can also be used with things, not only people.

Spanish uses definite articles more often than English does.

In English, you might say:

• Data limits affect mobile data

But Spanish often prefers:

• El límite de datos afecta a los datos móviles

Here:

• el goes with límite
• los goes with datos móviles

Leaving the articles out would usually sound less natural in a normal sentence.

Spanish often uses noun + de + noun where English uses two nouns together.

So:

• data limit → límite de datos
• credit card → tarjeta de crédito
• data plan → plan de datos

The word de often corresponds to English of, but in translation it may sound more natural as just a noun combination.

In everyday Spanish, especially in tech and phone contexts, datos is normally used in the plural to mean data.

So you get expressions like:

• datos móviles
• plan de datos
• consumo de datos
• límite de datos

The singular dato usually means a single piece of data or a fact/item of information.

Because móviles is an adjective here, and in Spanish adjectives usually come after the noun.

So:

• datos móviles = mobile data

Also, the adjective has to agree with the noun:

• dato móvil = singular masculine
• datos móviles = plural masculine

Since datos is masculine plural, the adjective must also be masculine plural: móviles.

Yes. In Spain, datos móviles is the standard everyday expression for mobile data.

People also often shorten it to just datos when the context is clear:

• He gastado todos los datos.
• No me quedan datos.

But the full form datos móviles is very common and completely natural.

The accent marks show where the stress goes:

• límite → stress on the first syllable: LÍ-mi-te
• móviles → stress on the first syllable: MÓ-vi-les

Without the written accent, Spanish stress rules would put the stress in a different place.

By contrast, datos does not need an accent mark because its natural stress already follows the normal rule:

• DA-tos

Yes, very often you can, if the context is clear.

For example, in a phone-plan conversation:

• Me he quedado sin datos.
• He consumido muchos datos.

But if you want to be explicit, especially for learners or in a technical explanation, los datos móviles is clearer.

So both are possible:

• los datos móviles = more explicit
• los datos = more natural when the situation already makes it obvious