En verano encendemos el aire acondicionado por la tarde para dormir mejor.

Spanish often drops subject pronouns because the verb ending already shows who is doing the action. Encendemos clearly means we turn on (1st person plural), so (nosotros) is optional and usually omitted unless you want emphasis or contrast.

Encendemos is the present indicative of encender for nosotros. In this context, the present tense commonly describes a habitual routine: In summer, we (usually) turn on the AC in the afternoon…

Yes. In many Latin American countries, prender (el aire) is very common for turn on appliances, alongside encender. Both work:

• En verano encendemos el aire acondicionado…
• En verano prendemos el aire acondicionado…

(Regional preference varies, but both are widely understood.)

Because aire is a masculine noun in Spanish, so it takes el. Acondicionado is an adjective/participle agreeing with aire (masculine singular), so it’s acondicionado (not acondicionada).

Yes. El aire acondicionado can refer to:

• the system/service (air conditioning in general), or
• the appliance/unit (the AC).

In everyday speech, many people shorten it to el aire when the context is clear.

Both exist, but they can feel slightly different:

• En verano = in summer (general, routine/season in general)
• En el verano = in the summer (often more specific—e.g., a particular summer, or contrasting with other seasons)

For general habits, En verano is very common.

Both can mean in the afternoon, but usage varies by region and style:

• por la tarde is very standard and widely used.
• en la tarde is also used in parts of Latin America, sometimes sounding more natural locally.

In many contexts they’re interchangeable, but por la tarde is a safe default.

In time expressions, por often marks a general time period or “during” part of the day:

• por la mañana (in the morning)
• por la tarde (in the afternoon)
• por la noche (at night)

It’s a set, very common pattern.

Para + infinitive expresses purpose: in order to… So para dormir mejor = in order to sleep better.
When the subject is the same (we turn it on + we sleep), Spanish typically uses para + infinitive rather than a full clause.

Yes. Para que + subjunctive is common when you express purpose, especially when emphasizing the result or when subjects differ. Here, since the subject is the same, para dormir mejor is simpler and very natural.
But para que durmamos mejor is also correct and means essentially the same: so that we sleep better.

Spanish doesn’t require the pronoun if the direct object is already stated. Since you already have el aire acondicionado, adding lo would be redundant:

• Natural: Encendemos el aire acondicionado.
• Also possible (more context-dependent): Lo encendemos por la tarde. (when el aire acondicionado is already known)

Yes, Spanish word order is fairly flexible. These all work, with slight changes in emphasis:

• En verano encendemos el aire acondicionado por la tarde para dormir mejor. (neutral)
• Por la tarde encendemos el aire acondicionado… (emphasizes afternoon)
• En verano, por la tarde, encendemos el aire acondicionado… (adds pauses/emphasis)