Por la tarde, otra gallina vuelve al gallinero para dormir.

In Spain, por la tarde is the normal way to say in the afternoon.

A few useful time expressions work like this:

• por la mañana = in the morning
• por la tarde = in the afternoon
• por la noche = at night / in the evening

You may hear en la tarde in some parts of Latin America, but for Spanish from Spain, por la tarde is the standard choice.

Also, in Spain la tarde can sometimes stretch later than English afternoon, so depending on context it may feel closer to late afternoon or even early evening.

The comma separates the time expression from the rest of the sentence.

It works a bit like an introductory phrase in English:

• In the afternoon, another hen returns to the henhouse to sleep.

In Spanish, that comma is very natural here, especially if the speaker wants a small pause. It is not always absolutely required with short introductory phrases, but it is perfectly normal.

Otra means another.

In Spanish, otro / otra normally does not take the indefinite article un / una before it, so:

• otra gallina = another hen

Not:

• una otra gallina

Also, otra is feminine singular because gallina is feminine singular.

Spanish word order is more flexible than English word order.

Here, otra gallina comes before vuelve because the sentence is presenting that hen as the subject in a clear, neutral way:

• Otra gallina vuelve al gallinero...

You could also hear:

• Vuelve otra gallina al gallinero...

But that changes the rhythm and focus slightly. The version in your sentence is the most straightforward and natural if you are simply describing what happens.

Vuelve is the third person singular present tense of volver.

So it can mean:

• returns
• comes back
• goes back

Because the subject is otra gallina, the verb must be singular:

• otra gallina vuelve

If the subject were plural, it would be:

• otras gallinas vuelven

Here, yes: volver al gallinero means to return to the henhouse.

But volver has another very important use:

• volver a + infinitive = to do something again

For example:

• vuelve a dormir = sleeps again
• vuelve a comer = eats again

That is different from your sentence:

• vuelve al gallinero = returns to the henhouse

So the structure matters:

• volver a + infinitive = do again
• volver a + place / volver al + noun = return to a place

Because a + el contracts to al in Spanish.

So:

• a + el gallinero → al gallinero

This contraction is required in normal Spanish.

Compare:

• Voy al mercado.
• Regresa al pueblo.

The only common contraction like this with articles is:

• a + el = al
• de + el = del

Gallinero means henhouse or chicken coop.

It is the place where hens or chickens are kept.

Related words:

• gallina = hen
• gallo = rooster
• pollo = chicken / chick, depending on context

So:

• otra gallina vuelve al gallinero = another hen returns to the coop

Para + infinitive expresses purpose:

• para dormir = to sleep / in order to sleep

So the sentence means the hen returns to the henhouse for the purpose of sleeping.

This is a very common structure:

• Fue a la tienda para comprar pan.
• Se sentó para descansar.

In this sentence, para dormir is especially clear because it avoids possible confusion with volver a dormir, which could mean to sleep again.

Yes, that can also be possible in Spanish, because a + infinitive is often used after verbs of movement to express purpose:

• va a comprar
• sale a correr
• sube a ver

So vuelve al gallinero a dormir could mean she returns to the henhouse to sleep.

However, para dormir is clearer here, because volver a dormir is also a common structure meaning to sleep again. Using para dormir removes that ambiguity.

Because Spanish often leaves out subject pronouns when they are not needed.

The verb form vuelve already tells you the subject is he/she/it or you formal, singular. And in this sentence, the noun otra gallina is already stated, so adding ella would be unnecessary.

Spanish normally prefers:

• Otra gallina vuelve al gallinero.

Rather than:

• Ella vuelve al gallinero.

unless you need extra emphasis or contrast.

Yes. Gallina means a hen, so it is specifically female.

The male is:

• gallo = rooster

That is why the adjective and any related words are feminine:

• otra gallina

If it were masculine, you would have:

• otro gallo

In most modern Spanish, including most of Spain, ll is pronounced like the y sound in yes.

So:

• gallina sounds roughly like ga-yee-na
• gallinero sounds roughly like ga-yee-ne-ro

In some regions, people still keep a distinction between ll and y, but most learners can safely pronounce ll like y.