Learn Hardcore Spanish (Latin America): Ella piensa que debería haber escuchado a su mentora con más atención. - She thinks she should have listened to her mentor more carefully.

Debería is the simple conditional of deber (to ought to / should).
Haber escuchado is a perfect infinitive (literally “to have listened”).

Put together, debería haber escuchado is very close to English “should have listened.”

Grammar-wise:

debería – conditional mood (3rd person singular)
haber escuchado – perfect infinitive (used to refer to a prior action)

So the structure is:
[deber in conditional] + [perfect infinitive] = “should have done X (in the past)”

Why is it debería haber escuchado and not debería escuchar?

Because the regret is about something that didn’t happen in the past.

debería escuchar = she should listen (now / in general, present or future obligation)
debería haber escuchado = she should have listened (but she didn’t, and now she regrets it)

The haber + past participle (haber escuchado) clearly puts the action before the point in time of “thinking” and marks it as a past, completed, but failed obligation.

Why is it haber escuchado and not ha escuchado?

After debería, you need an infinitive, not a conjugated verb.

Correct: debería haber escuchado
- haber is in the infinitive,
- escuchado is a past participle.
Incorrect here: debería ha escuchado
- ha is a conjugated form (3rd person singular of haber in the present perfect), and two conjugated verbs can’t appear like this in a row in standard Spanish.

Think of it as parallel to English:

Spanish: debería haber escuchado
English: should have listened
- You also don’t say “should has listened.”

Why is piensa in the present tense if she’s talking about a past mistake?

Because piensa describes what she thinks now, in the present:

Ella piensa = She thinks (now)
que debería haber escuchado… = that she should have listened… (back then)

So the main clause is in the present (her current thought), and the subordinate clause refers to a past situation using debería haber escuchado.

If you wanted to narrate this all in the past, you could say:

Ella pensó que debería haber escuchado a su mentora con más atención.
She thought she should have listened to her mentor more carefully.

Could you say cree que instead of piensa que? Is there any difference?

Yes, you can say:

Ella cree que debería haber escuchado a su mentora con más atención.

Both piensa que and cree que often translate as “she thinks that” or “she believes that.”

Nuance:

pensar que – slightly more about considering / thinking something is the case.
creer que – slightly more about believing something to be true.

In everyday conversation, the difference is small; many speakers use them almost interchangeably here.

Why is there an a before su mentora: escuchado a su mentora?

That a is the “personal a” in Spanish.

You generally use a before a direct object that is:

a specific person
or a personified being (like a pet you treat as a person)

Here, su mentora (her mentor, a specific person) is the direct object of escuchar, so you add a:

escuchar a su mentora = to listen to her mentor

Without the person:

escuchar música (no a, because it’s not a person)
escuchar a María (with a, because María is a person)

Why is it su mentora and not su mentor?

Mentora is the feminine form of mentor in modern Spanish.

su mentor – her mentor (male) or unspecified gender (traditional default)
su mentora – her female mentor

In much of Latin America, using feminine forms like mentora, doctora, profesora, etc. is common and increasingly preferred when referring to women.

Can the subject Ella be omitted? Is Piensa que debería haber escuchado… also correct?

Yes, it’s completely correct to say:

Piensa que debería haber escuchado a su mentora con más atención.

In Spanish, the subject pronoun (yo, tú, él, ella, etc.) is often dropped because the verb ending already shows who the subject is.

Including Ella:

can help avoid ambiguity (for example, if you were talking about more than one person),
or can add a bit of emphasis on she (as opposed to someone else).

Why is it con más atención and not something like más atentamente?

Both are possible, but they feel slightly different:

con más atención – literally “with more attention,” sounds natural and common; it’s like saying “more carefully” or “more attentively” in a neutral, everyday way.
más atentamente – literally “more attentively,” a bit more adverb-like and sometimes sounds slightly more formal or stylistic.

So you could also say:

Ella piensa que debería haber escuchado a su mentora más atentamente.

The original con más atención is very typical in conversation.

Could you use an object pronoun: debería haberla escuchado instead of haber escuchado a su mentora?

Yes. Both are correct, and often you’ll hear a combination in speech.

Options:

Ella piensa que debería haber escuchado a su mentora con más atención.
– fully explicit; no pronoun.
Ella piensa que debería haberla escuchado con más atención.
– la refers to su mentora; the person has usually been mentioned earlier.
In spoken Spanish, some people even double up (especially in some regions):
Ella piensa que debería haberla escuchado a su mentora con más atención.
– This “doubling” of pronoun + noun is common in many varieties of Spanish, even though grammar books may mark it as redundant in some contexts.

Placement rule with compound forms:

Pronoun before the first conjugated verb:
Ella la debería haber escuchado…
Or attached to the infinitive/gerund (here, to haber isn’t done; instead you attach to the main infinitive in other constructions, but here you attach to haber because it’s the infinitive right after the conjugated verb):
Ella debería haberla escuchado…

Should the verb after piensa que be in the subjunctive? Why is it debería haber escuchado (indicative form) and not subjunctive?

With piensa que and cree que, Spanish normally uses the indicative, because these verbs express belief / certainty, not doubt:

Ella piensa que debería haber escuchado… – indicative (her belief about reality)

You would expect the subjunctive after no piensa que / no cree que / duda que, etc., which express negation, doubt, or uncertainty:

Ella no piensa que deba haberla escuchado.
She doesn’t think she should have listened to her.

So:

piensa que + indicative – standard when stating something the subject believes is true.
no piensa que + subjunctive – standard for denying or doubting that something is true.