Learn Hardcore Spanish (Latin America): Ojalá que hayamos aprendido lo esencial de esta lección. - I hope we have learned the essential parts of this lesson.

Because ojalá triggers the subjunctive. Hayamos aprendido is the present perfect subjunctive, used for wishes/hope about a completed action. Hemos aprendido is indicative and would be a statement of fact, not a hope: “We have learned.”

What exactly is the tense/mood of hayamos aprendido, and when do I use it?

It’s the present perfect subjunctive: auxiliary haber in the present subjunctive (e.g., haya/hayas/haya/hayamos/hayan) + past participle (aprendido). Use it after triggers of emotion, doubt, hope, etc., when the action is viewed as completed by now or very recently.

Could I say Ojalá (que) aprendamos lo esencial instead? What’s the difference?

Yes.

Ojalá (que) aprendamos: hope about learning from now into the near future (not completed yet).
Ojalá (que) hayamos aprendido: hope that, by this point, the learning is already done.

Is que required after ojalá?

No. Both are correct: Ojalá que… and Ojalá…. In parts of Latin America you’ll also hear colloquial ojalá y….

Can I use the indicative after ojalá?

Standard Spanish uses the subjunctive after ojalá. You may hear colloquial/regional indicative with ojalá y (e.g., in Mexico), but in careful speech and writing stick to the subjunctive: Ojalá (que) hayamos aprendido, not hemos.

What does lo esencial mean, and why lo?

Lo is the neuter article. Lo + adjective turns the adjective into an abstract noun: lo esencial = “the essential part/what’s essential.” It’s not masculine; it’s neuter and doesn’t agree with any noun.

Could I say el esencial or los esenciales?

Not here. El esencial sounds ungrammatical in this sense. You could say something like los puntos esenciales (“the essential points”), but lo esencial is the natural way to say “the essentials/the essential part.”

If I want to replace lo esencial with a pronoun, which one do I use and where do I put it?

Use the direct object pronoun lo, and place it before the verb: Ojalá (que) lo hayamos aprendido.

Why is it de esta lección and not en esta lección?

De marks content/possession (“the essentials of this lesson”). En would mean “in this lesson” and shifts the focus to location/context; in this sentence de is the idiomatic choice.

Is the accent on esta necessary? Should it be ésta?

Use esta without an accent in modern standard Spanish. The accented form ésta is old-fashioned and only used to avoid rare ambiguities. Here, esta is correct.

How do I pronounce the tricky words?

Approximate Latin American pronunciations:

ojalá: oh-ha-LAH (the letter j is a strong h-sound)
hayamos: ah-YAH-mohs (initial h is silent)
aprendido: ah-pren-DEE-doh
lección: lek-SYON (the c before i is like s)

Common spelling pitfall: hayamos (from haber) vs. hallamos (from hallar, “we find”).

Is ojalá formal or informal? How does it compare to Espero que…?

Ojalá is neutral and widely used in both speech and writing; it’s a bit more emotive/intense than Espero que…. Both require the subjunctive: Ojalá/Espero que hayamos aprendido…

Where would I put words like ya (“already”)?

Place them before the auxiliary: Ojalá (que) ya hayamos aprendido lo esencial… This emphasizes that you hope it’s already done.

How do I express regret about the past (wish something had happened but didn’t)?

Use the past perfect (pluperfect) subjunctive: Ojalá (que) hubiéramos/hubiésemos aprendido lo esencial… This implies it didn’t happen and you regret it.

What are the forms of haber for the present perfect subjunctive?

yo: haya
tú: hayas
él/ella/usted: haya
nosotros: hayamos
ustedes/ellos/ellas: hayan
Add a past participle: haya aprendido, hayamos visto, etc.

Does the past participle (aprendido) change to agree with nosotros?

No. With auxiliary haber, the participle is invariable: hemos/hayamos aprendido (never aprendidos). It only agrees when used as an adjective (e.g., los temas aprendidos).

Do I need a comma after Ojalá?

No. Write Ojalá (que) hayamos aprendido… without a comma.