¿Podría usted decirme si es mejor esperar hasta que salga el caballo del establo?

Podría makes the request more polite and less direct.

• ¿Puede usted decirme...? = Can you tell me...?
• ¿Podría usted decirme...? = Could you tell me...?

In Spanish, the conditional form podría is very commonly used for polite requests, just like could in English. It does not mean the action is only hypothetical here; it is mainly a softening device.

No, you do not have to include usted.

Spanish often leaves subject pronouns out because the verb already shows the person:

• ¿Podría usted decirme...?
• ¿Podría decirme...?

Both are correct. Including usted adds formality or emphasis. In Spain, usted is used in formal situations, but in everyday speech it is often omitted even when the tone is still polite.

Decirme is decir + me, meaning to tell me.

When you have a conjugated verb plus an infinitive, object pronouns can often go in either place:

• ¿Podría decirme...?
• ¿Me podría decir...?

Both are correct.

What you cannot do is put me directly in front of the infinitive by itself:

• me decir ❌

So in this sentence, decirme is perfectly normal and very common.

Here, si means if or whether.

• decirme si es mejor... = tell me if / whether it is better...

It is not the same as sí with an accent.

• si = if / whether
• sí = yes

That accent matters.

After es mejor, Spanish often uses an infinitive when speaking generally about what is better to do:

• Es mejor esperar. = It’s better to wait.

If Spanish wants to introduce a different subject and make it more personal, it often uses que + subjunctive:

• Es mejor que espere. = It’s better that you wait.
• Es mejor que esperemos. = It’s better that we wait.

So:

• es mejor esperar = general statement
• es mejor que + subjunctive = more specific about who should do it

Because the horse has not come out yet. The action is still pending, so Spanish uses the subjunctive after hasta que.

• hasta que salga = until it comes out
• salga is the subjunctive of salir

A very common rule is:

• hasta que + subjunctive for a future or not-yet-completed action
• hasta que + indicative for an action viewed as completed or factual

Compare:

• Es mejor esperar hasta que salga el caballo.
  The horse has not come out yet.
• Esperé hasta que salió el caballo.
  Now it is a completed past event.

Salga is the present subjunctive, third person singular, of salir.

A few forms of salir:

• sale = present indicative, he/she/it comes out
• salga = present subjunctive, that he/she/it come out

Here it is used because hasta que is referring to an action that is still in the future from the speaker’s point of view.

Because de + el contracts to del in Spanish.

• de + el = del
• a + el = al

So:

• del establo = from/out of the stable

This contraction is normally mandatory. Saying de el establo would be wrong in standard Spanish.

Both word orders are possible, but salga el caballo del establo sounds quite natural in Spanish.

Spanish has more flexible word order than English, especially in subordinate clauses and with verbs of movement like salir. Putting the verb before the subject can sound smoother or slightly more natural in certain contexts.

So both are grammatical:

• hasta que salga el caballo del establo
• hasta que el caballo salga del establo

The second one may feel more straightforward to an English speaker, but the version in the sentence is fully normal.

Yes, it sounds fairly formal because of podría and usted.

In Spain, a speaker might say this in a polite or respectful situation. In everyday informal speech, especially with someone you know, you would more likely hear tú forms, for example:

• ¿Podrías decirme si es mejor esperar hasta que salga el caballo del establo?

Or even more simply:

• ¿Crees que es mejor esperar hasta que salga el caballo del establo?

So the original sentence is correct, but it has a formal, careful tone.