Una avería en la red eléctrica causa un apagón.

Avería means a fault, breakdown, or malfunction. In this sentence, it refers to a problem in the electrical system.

It is commonly used for machines, vehicles, appliances, and technical systems:

• una avería del coche = a car breakdown
• una avería en el ascensor = a fault in the elevator
• una avería en la red eléctrica = a fault in the power grid

Because Spanish nouns have grammatical gender:

• avería is feminine → una avería
• apagón is masculine → un apagón

The article has to match the noun:

• un for masculine singular nouns
• una for feminine singular nouns

En is used because the fault happens in or within the electrical grid.

• una avería en la red eléctrica = a fault in the power grid

This sounds natural when talking about where the problem is located.

You may sometimes also hear avería de la red eléctrica, but that usually sounds more like a failure of the electrical grid as a whole. In this sentence, en is the most straightforward and natural choice.

Literally, red eléctrica means electrical network.

In natural English, that is usually:

• power grid
• electrical grid
• power network

Notice the word order:

• red = network/grid
• eléctrica = electrical

In Spanish, adjectives usually come after the noun, so red eléctrica is normal.

Because the subject is singular: Una avería en la red eléctrica.

The main noun in the subject is avería, which is singular, so the verb must also be singular:

• Una avería ... causa ...

If the subject were plural, the verb would change:

• Varias averías en la red eléctrica causan apagones.

Causa is the present tense of causar: it causes.

The present tense is often used in Spanish to state:

• general facts
• explanations
• news-style statements

So this sentence can mean something like:

• A fault in the power grid causes a blackout
• A fault in the power grid is causing a blackout, depending on context

Spanish often uses the simple present where English might use either the simple present or present progressive.

Yes, apagón is a very common word for a blackout or power outage, especially when it is sudden or affects a large area.

In many Latin American countries, you may also hear:

• corte de luz = power cut / power outage
• corte eléctrico = electrical outage

So:

• un apagón often suggests a blackout
• un corte de luz is also very common in everyday speech

Yes. Apagón is related to apagar, which means to turn off or to extinguish.

Examples:

• apagar la luz = to turn off the light
• apagarse = to go out / switch off

So apagón is the noun used for a major instance of things going out, especially electricity.

In this sentence, it does use one: un apagón.

That is because the speaker is referring to a blackout as the result of the fault. In Spanish, singular countable nouns usually need an article when used this way.

So:

• causa un apagón = causes a blackout

Leaving out the article here would sound incomplete or unnatural.

Yes. Provoca is a very natural alternative.

• Una avería en la red eléctrica causa un apagón.
• Una avería en la red eléctrica provoca un apagón.

Both mean basically the same thing: a fault in the power grid causes a blackout.

Sometimes provocar can sound a little more like bring about or trigger, but in this context both are normal.

Because in Spanish, most adjectives normally come after the noun.

So:

• red eléctrica = electrical grid
• energía eléctrica = electrical energy
• corriente eléctrica = electric current

This is one of the basic differences from English, where adjectives usually come before the noun.

Yes, but the original sentence is the most neutral and natural order.

Normal order:

• Una avería en la red eléctrica causa un apagón.

Other possible versions:

• Un apagón lo causa una avería en la red eléctrica.
  This puts more emphasis on un apagón.
• El apagón fue causado por una avería en la red eléctrica.
  This is passive and sounds more formal.

Spanish allows more flexibility in word order than English, but the basic subject-verb-object order is usually the clearest for learners.

The written accents show where the stress goes:

• avería → stress on rí: a-ve-RÍ-a
• apagón → stress on gón: a-pa-GÓN

Why the accents are there:

• apagón ends in n, so without an accent it would normally be stressed on the second-to-last syllable. The accent mark shows that the stress is instead on the last syllable.
• avería needs the accent to show the stress and the pronunciation pattern clearly.

These accents are important because they tell you how to pronounce the words correctly.

It is natural and correct, but it sounds a bit like:

• a news report
• an official explanation
• a written statement

In everyday conversation, many speakers might say something simpler, such as:

• Hubo un apagón por una avería en la red eléctrica. = There was a blackout because of a fault in the power grid.
• El apagón fue por una falla en la red eléctrica. = The blackout was due to a fault in the power grid.

In much of Latin America, falla is also very common instead of avería in this kind of context.