Learn Hardcore Spanish (Latin America): El fracaso enseña una lección importante.

Spanish often uses the definite article to talk about things in a general, abstract sense. El fracaso means “failure (as a concept).” Omitting the article sounds unnatural. You could also generalize with the plural: Los fracasos enseñan…—both are fine.

Is fracaso masculine or feminine? What’s its plural?

Masculine. Singular: el fracaso / un fracaso. Plural: los fracasos.

What form is enseña? Why isn’t there a subject pronoun?

enseña is 3rd person singular present indicative of enseñar. The subject is El fracaso, so no subject pronoun is needed. Note the difference between the article el and the pronoun él (with accent) “he.”

How do I say “Failure teaches us/you/them an important lesson”?

Use an indirect object pronoun before the verb:

El fracaso nos enseña una lección importante. (us)
El fracaso te enseña… (you, singular informal)
El fracaso les enseña… (them/you plural)

If you also replace “lesson” with a direct-object pronoun: El fracaso te la enseña.

Do I need the preposition a to mark whom something is taught?

Yes, when naming the person: enseñar algo a alguien.

El fracaso enseña una lección importante a todos.
El fracaso les enseña una lección importante a los emprendedores. Doubling the indirect object is normal: les … a los emprendedores.

Why una lección and not la lección?

Una is indefinite (an unspecified lesson). La lección would refer to a specific, known lesson: El fracaso enseña la lección que nadie olvida.

Why is the adjective after the noun? Can it go before?

Descriptive adjectives usually follow: una lección importante. Placing it before can add emphasis or a subjective tone: una importante lección (common in headlines or rhetoric). Both are correct.

How do I pronounce the tricky parts?

fracaso: single-tap r; c before a = k → fra-KA-so.
enseña: ñ = “ny” → en-SEH-nyah.
lección: cc = k + s; stress on the last syllable → lek-SYON.
importante: im-por-TAN-te. Note: In most of Latin America, c/z before e/i sound like s (not “th” as in Spain).

Why does lección have an accent?

Words ending in a vowel, n, or s are normally stressed on the next-to-last syllable. lección ends in n but is stressed on the last syllable (-ción), so it needs the written accent: lección.

If I replace una lección importante with a pronoun, which one and where does it go?

Use the feminine direct-object pronoun la:

El fracaso la enseña.
With an IO too: El fracaso te la enseña. Pronouns go before a conjugated verb (or attached to an infinitive/gerund/affirmative command).

Can I use the infinitive as the subject, like Fracasar enseña…?

Yes. Fracasar enseña una lección importante. This focuses on the act of failing rather than the abstract noun. It’s natural in Spanish.

Is enseñar una lección idiomatic, or should I say something else?

It’s fine, but you’ll also hear:

dar(le) una lección (a alguien) = to teach someone a lesson (often corrective).
dejar una enseñanza (very common in Latin America): El fracaso deja una enseñanza importante.
Del fracaso se aprende. (“One learns from failure.”)

What’s the difference between fracaso, derrota, error, and fallo?

fracaso: a failed outcome (broad).
derrota: a defeat, usually in competition/conflict.
error: a mistake; a wrong action/decision.
fallo: a mistake/defect; also a “legal ruling.”

Can I front the object for emphasis?

You can, but it sounds marked or literary here:

Neutral: El fracaso enseña una lección importante.
Marked: Una lección importante nos enseña el fracaso. Use fronting sparingly in everyday speech.

If I say El fracaso enseña que…, which mood follows?

Indicative, because you’re asserting a fact: El fracaso enseña que la perseverancia es clave.

Can enseñar appear without an explicit object, like El fracaso enseña?

Yes. The object is understood from context. This elliptical style is common in aphorisms and headlines.