Hablamos al respecto ayer.

Because hablamos can be either:

• present: we speak / we are speaking
• preterite past: we spoke / we talked

In this sentence, ayer means yesterday, so the time expression makes it clear that hablamos is past here:

• Hablamos al respecto ayer. = We talked about it yesterday.

This is very common in Spanish: context tells you which meaning is intended.

Only in form, not always in meaning.

The written form hablamos is the same for:

• nosotros hablamos = we speak
• nosotros hablamos = we spoke

But in real sentences, context usually removes the ambiguity:

• Hablamos español en casa. = present
• Hablamos ayer. = past

If there is no context at all, then yes, it could be ambiguous.

Al respecto is a fixed expression meaning:

• about it
• about that
• regarding that
• on that matter

So in this sentence, Hablamos al respecto ayer means something like:

• We talked about it yesterday
• We discussed that yesterday

It often sounds a bit more formal or neutral than de eso.

Because al respecto is an idiomatic expression. It is simply the standard phrase Spanish uses.

Here, al = a + el, but learners usually should treat al respecto as one chunk of language with the meaning about that / regarding that.

So it is best to learn it as a set phrase:

• No dijo nada al respecto. = He/She said nothing about it.
• Hablamos al respecto ayer. = We talked about it yesterday.

They are related, but they are not used in the same way.

• al respecto = about that / regarding that matter
• respecto a = with regard to / regarding
  • a noun or phrase

Examples:

• No tengo nada que decir al respecto.
  = I have nothing to say about it.

• Respecto a este tema, no estoy de acuerdo.
  = Regarding this topic, I don’t agree.

So in your sentence, al respecto refers back to something already mentioned.

Yes, absolutely.

• Hablamos de eso ayer. = very natural, everyday way to say We talked about that yesterday
• Hablamos al respecto ayer. = also correct, but a bit more formal or polished

So both are fine, but de eso is usually more conversational.

Yes. Sobre eso also means about that.

So these are all possible:

• Hablamos de eso ayer.
• Hablamos sobre eso ayer.
• Hablamos al respecto ayer.

Very roughly:

• de eso = most everyday
• sobre eso = also common, sometimes slightly more explicit
• al respecto = a little more formal or abstract

Because Spanish word order is flexible.

Ayer can go in different positions:

• Hablamos al respecto ayer.
• Ayer hablamos al respecto.

Both are correct. The difference is mainly one of emphasis or rhythm.

• Ayer hablamos al respecto puts more focus on yesterday
• Hablamos al respecto ayer sounds more like a neutral statement ending with the time

Because Spanish often leaves out subject pronouns when the verb already shows who the subject is.

• Hablamos already tells you it is we
• So nosotros is not necessary

You could say:

• Nosotros hablamos al respecto ayer

But that usually adds emphasis, contrast, or clarity. For example:

• Nosotros hablamos al respecto ayer, pero ellos no.
  = We talked about it yesterday, but they didn’t.

Because ayer usually points to a completed action at a specific time in the past.

The preterite hablamos fits that idea:

• Hablamos al respecto ayer. = We talked about it yesterday.
  A completed event.

The imperfect would be hablábamos, which would suggest an ongoing, repeated, or background action:

• Hablábamos al respecto cuando llegó Marta.
  = We were talking about it when Marta arrived.

So for a single finished conversation yesterday, the preterite is the natural choice.

It is correct in both Spain and Latin America.

That said, in everyday conversation, many speakers might more naturally say:

• Hablamos de eso ayer.

The version with al respecto may sound a bit more formal, careful, or written-style, but it is still perfectly normal and understandable in Spain.

Usually, al respecto refers to a topic, issue, situation, or matter that has already been mentioned.

So it works best for things like:

• a problem
• a decision
• a topic
• a question
• a situation

Example:

• Hubo un problema y hablamos al respecto.
  = There was a problem and we talked about it.

If you mean about a person, Spanish often prefers something more direct like:

• Hablamos de él ayer. = We talked about him yesterday.
• Hablamos de ella ayer. = We talked about her yesterday.

A simple pronunciation guide would be:

• Hablamos al respecto ayer
• roughly: ah-BLA-mos al res-PEK-to ah-YER

A few useful points:

• h in hablamos is silent
• b in hablamos is a soft Spanish b
• ll in hablamos is just l + l, because they are in separate syllables: ha-bla-mos
• ayer in Spain is pronounced with a y-like sound at the start: a-YER

Yes, depending on context.

Hablar de algo is literally to talk about something, but in English, natural translations can vary:

• We talked about it yesterday
• We discussed it yesterday
• We spoke about it yesterday

If the conversation was more serious or focused, discussed can sound very natural.