En la montaña vemos molinos de viento que producen energía eólica para la ciudad.

Both are correct; the difference is focus and style, not grammar.

• En la montaña vemos molinos de viento…
  – Literal: On the mountain we see windmills…
  – Emphasis: where the action happens (the location). The sentence starts by setting the scene.

• Vemos molinos de viento en la montaña…
  – Literal: We see windmills on the mountain…
  – Emphasis: the action (we see windmills), and then you add where.

Spanish word order is fairly flexible. Moving en la montaña to the front is natural when you want to highlight the place as the background of your description, a bit like English “On the mountain, we see windmills…”

In Spanish, you normally need the definite article with singular countable nouns when speaking in general:

• en la montaña = on the mountain / in the mountains (as a type of environment)
• en la ciudad = in the city
• en el campo = in the countryside

Saying “en montaña” sounds incomplete and unnatural in standard Spanish.

Note that en la montaña can mean:

• a specific mountain previously known from context, or
• the mountain environment in general (like “up in the mountains” in English).

Context usually makes clear which meaning is intended.

Ver and mirar are not interchangeable in all contexts:

• ver = to see (perceive with your eyes, often without intentionality)
• mirar = to look (at something deliberately)

In this sentence:

• En la montaña vemos molinos de viento…
  → On the mountain we see windmills… (they are there in the landscape)

If you say:

• En la montaña miramos molinos de viento…
  It sounds like: On the mountain we (deliberately) look at / observe windmills…
  This is possible but changes the nuance; it sounds a bit more like an activity: you are there to look at the windmills.

For a neutral description of what is visible in the landscape, ver is the natural choice.

Spanish is a pro‑drop language: you usually omit subject pronouns because the verb ending already shows the subject.

• vemos = we see (1st person plural)
• So Nosotros is not necessary.

Both are correct:

• Vemos molinos de viento… (most natural)
• Nosotros vemos molinos de viento… (correct but only used for emphasis or contrast, e.g. Nosotros vemos molinos de viento, ellos no – We see windmills, they don’t.)

In your sentence, there is no contrast, so the pronoun is normally dropped.

Molinos de viento is a noun + prepositional complement:

• molinos = plural of molino (masculine noun, mill)
• de viento = of wind / wind‑ (prepositional phrase specifying what kind of mills)

Spanish often uses noun + de + noun where English uses compound nouns:

• molino de viento = windmill
• casa de campo = country house
• tarjeta de crédito = credit card

So molinos de viento literally means mills of wind, i.e. windmills. There is no single-word compound here; the de construction is the normal way to form this idea.

The noun viento is singular because it refers to the substance / type of energy (wind in general), not individual “winds”:

• molinos de viento = mills for wind (as a phenomenon)
• Making it plural (molinos de vientos) would sound strange, as if each mill were dedicated to multiple separate “winds”.

This is similar to:

• vasos de agua = glasses of water (not de aguas in this context)
• zapatos de cuero = leather shoes (not de cueros)

When a noun is used like a material or generic element, it often stays singular after de.

Here que is a relative pronoun referring back to molinos de viento:

• molinos de viento que producen energía eólica…
  = windmills *that produce wind energy…*

So:

• que = that / which
• It introduces a relative clause: que producen energía eólica para la ciudad.

You could replace it with los cuales in very formal or written Spanish:

• molinos de viento, los cuales producen energía eólica…

But:

• This sounds more formal or technical.
• In normal speech and writing, que is by far the most natural option.

Spanish present simple is often used where English uses either present simple or present continuous. It’s very common to use it for:

• general facts
• habitual actions
• ongoing processes

Here, producen energía eólica means:

• They produce wind energy
  → describing what they generally do, their function.

You could say:

• …molinos de viento que están produciendo energía eólica…
  But this would focus more on the action happening right now, as you look at them, and it sounds more specific and less like a general description of their role.

For a neutral, factual description, producen is the standard choice.

• energía eólica is the standard technical term for wind energy.

  • eólica comes from Eolo (Aeolus), the god of the winds in Greek mythology.
  • Literally: Aeolian energy → wind energy.

• energía del viento literally = energy of the wind
  – It’s understandable and grammatically correct, but:

  • sounds more descriptive/colloquial
  • is not the usual term you’d see in textbooks, news, or technical contexts in Spain.

In Spain, energía eólica is the normal, idiomatic expression.

In Spanish, adjectives typically go after the noun:

• energía eólica
• coche eléctrico
• ciudad grande

Putting the adjective before the noun is less common and usually adds a special nuance (emotional, stylistic, poetic). For technical terms like energía eólica, the neutral, standard order is:

noun + adjective → energía eólica

Each preposition changes the meaning:

• para la ciudad
  – para = for (the benefit of / destined for)
  – energía eólica para la ciudad = wind energy for the city (the city is the beneficiary or destination).

• a la ciudad
  – usually means to the city (movement or direction).
  – Energía eólica a la ciudad is not idiomatic here.

• por la ciudad
  – often means through / around / because of the city.
  – energía eólica por la ciudad would be confusing or incorrect in this context.

So para is the correct choice to express the idea that the energy is for the city’s use.

Just like with la montaña, Spanish normally uses the definite article with singular, countable nouns, even when speaking in a general way:

• la ciudad = the city (often meaning “the city in question / the city we’re talking about”)
• Saying only ciudad would sound incomplete here.

Exceptions (no article) appear in certain fixed expressions (en casa, en clase, en prisión, etc.) or after some verbs with professions or roles (soy médico, es profesor). Ciudad doesn’t fall into one of those exception patterns in this sentence, so la ciudad is required.

The accents mark the stressed syllable, breaking the default stress rules.

1. energía

   • Without accent, energia would be stressed on the second‑to‑last syllable: e‑ner‑GI‑a
   • With accent, it is: e‑ner‑GÍ‑a
   • Pronunciation: e‑ner‑GEE‑a (four syllables).

2. eólica

   • Without accent, eolica would be stressed on the second‑to‑last syllable: e‑O‑li‑ca
   • With accent, it is: e‑Ó‑li‑ca
   • Pronunciation: eh‑OH‑lee‑ka (four syllables: e‑Ó‑li‑ca).

The written accents ensure correct pronunciation and distinguish them from how they would be stressed by default.