Preparamos el repertorio para mejorar la afinación.

Preparamos is the 1st person plural form of preparar (to prepare), so it means we prepare.

A very important detail: preparamos can mean either:

• we prepare / we are preparing (present tense), or
• we prepared (preterite / simple past)

The form is identical in both tenses. You tell which one it is from context.

So this sentence could mean either:

• We prepare the repertoire to improve intonation/tuning, or
• We prepared the repertoire to improve intonation/tuning

Without more context, both are grammatically possible.

Spanish often leaves out subject pronouns because the verb ending already shows who the subject is.

• preparamos already tells you the subject is we
• so nosotros preparamos is possible, but usually unnecessary

You would add nosotros only if you want to give emphasis, show contrast, or avoid confusion.

For example:

• Preparamos el repertorio... = neutral
• Nosotros preparamos el repertorio, no ellos. = We prepared the repertoire, not them

In Spanish, the definite article (el, la, los, las) is used more often than in English.

So el repertorio means:

• the repertoire

Even when English might sometimes sound more natural without the, Spanish often still uses the article.

Here, el repertorio refers to a specific repertoire or the repertoire relevant to the group, class, choir, band, etc.

Para + infinitive is a very common Spanish structure that expresses purpose.

So:

• para = for / in order to
• mejorar = to improve

Together:

• para mejorar = to improve / in order to improve

In this sentence, it explains why the repertoire is being prepared.

A useful pattern to remember is:

• Hacemos X para Y. = We do X in order to Y.

Examples:

• Estudio para aprender. = I study to learn.
• Ensayamos para tocar mejor. = We rehearse to play better.

Because after para to express purpose, Spanish normally uses the infinitive when the subject is general or the same as the main clause.

So:

• para mejorar = to improve
• not para mejoramos

After para, a conjugated verb like mejoramos would be wrong here.

Compare:

• Preparamos el repertorio para mejorar la afinación. = We prepare the repertoire to improve intonation.
• Preparamos el repertorio y mejoramos la afinación. = We prepare the repertoire and we improve intonation.

The first gives a purpose. The second gives a second action.

In a musical context, la afinación usually means:

• tuning
• intonation

The best English choice depends on context:

• If you are talking about singers or instrumentalists playing/singing in tune, intonation is often a good translation.
• If you are talking more generally about being in tune, tuning may also work.

So in this sentence, mejorar la afinación means improving how accurately the music is sung or played in tune.

Normally, it refers to the performers' tuning/intonation, not to some property of the repertoire itself.

So the meaning is usually:

• We prepare the repertoire in order to sing/play it with better intonation.

Spanish does not need to spell that out fully if the musical context makes it obvious.

If you wanted to make the performers more explicit, you could say something like:

• Preparamos el repertorio para mejorar nuestra afinación.
• Preparamos el repertorio para mejorar la afinación del coro.

But the original sentence sounds natural without that extra detail.

Yes. Repertorio is often translated as repertoire, but in real use it can refer to:

• the collection of pieces a performer or group knows
• the set of works being prepared for a performance
• sometimes something close to setlist or program, depending on context

So in a choir, orchestra, band, or music class, el repertorio usually means the pieces being worked on.

Yes, very much. It sounds especially natural in contexts like:

• a choir rehearsal
• an orchestra or band practice
• music lessons
• vocal training
• ensemble preparation

That is because both repertorio and afinación are very common words in musical settings.

Afinación is pronounced roughly like a-fi-na-THYON in most of Spain, because c before i is usually pronounced like th in Castilian Spanish.

In many Latin American accents, it would sound more like a-fi-na-SYON.

The written accent in -ción shows where the stress goes:

• a-fi-na-CIÓN

It needs the accent mark because words ending in n, s, or a vowel normally have stress on the second-to-last syllable, but here the stress is on the last syllable.

The core meaning of para is often related to for, but in this sentence the most natural English translation is to or in order to.

So:

• para mejorar la afinación = to improve intonation
• more literally: for improving intonation

English usually prefers to improve here, while Spanish naturally uses para + infinitive.

Because preparamos can be either present or preterite, you can add context or change the wording to make the time clearer.

To make it clearly present:

• Ahora preparamos el repertorio para mejorar la afinación.
• Estamos preparando el repertorio para mejorar la afinación.

To make it clearly past:

• Ayer preparamos el repertorio para mejorar la afinación.
• Preparamos el repertorio la semana pasada para mejorar la afinación.

So the ambiguity is normal, and Spanish speakers rely on context to understand it.