Learn Hardcore Spanish (Latin America): Yo sí comprendo la lección hoy.

Yo comprendo la lección hoy.
= Neutral statement: I understand the lesson today.
Yo sí comprendo la lección hoy.
= Emphatic / contrastive: I *do understand the lesson today*, maybe contrary to what someone thinks, or compared to another time/person.

So sí is optional, but it adds emphasis.

Is the yo necessary? Can I just say Sí comprendo la lección hoy?

You can absolutely drop yo:

Sí comprendo la lección hoy.
Comprendo la lección hoy.

Spanish usually omits subject pronouns because the verb ending (comprendo) already shows the subject is yo.

When is yo used?

For emphasis or contrast:
Yo sí comprendo la lección hoy, pero ellos no.
I do understand the lesson today, but they don’t.
To clarify in a longer context.

Grammatically, all of these are correct:

Yo sí comprendo la lección hoy.
Sí comprendo la lección hoy.
Yo comprendo la lección hoy.
Comprendo la lección hoy.

What’s the difference between comprender and entender?

In practice, in Latin American Spanish:

comprender ≈ entender
Both usually mean “to understand.”

General tendencies (not strict rules):

entender is more common in everyday, informal speech.
comprender can sound slightly more formal, or closer to “to comprehend,” “to grasp deeply.”

Examples:

No entiendo la lección. / No comprendo la lección.
I don’t understand the lesson.
Ahora comprendo lo que quieres decir.
Now I (really) comprehend what you mean.

But most of the time, learners can treat them as synonyms.

Why is it la lección and not el lección?

Because lección is a feminine noun in Spanish.

It uses the article la: la lección.
Many nouns ending in -ción are feminine:
- la nación (nation)
- la canción (song)
- la información (information)

Also note the stress and accent: lección is stressed on -cción and has an accent on ó.

Why do we need the article la at all? In English I might just say “I understand the lesson.”

Spanish uses definite articles (el, la, los, las) more often than English.

In comprendo la lección, la points to a specific lesson both the speaker and listener know about (e.g., today’s lesson in class).

Usually you cannot omit the article here:

❌ Comprendo lección hoy. (incorrect)
✅ Comprendo la lección hoy.

You might omit it only if you change the structure, for example:

Comprendo la lección de hoy. (I understand today’s lesson.)
Comprendo esta lección. (I understand this lesson.)

But some determiner (article, esta, esa, etc.) is normally needed.

Where can I put hoy in the sentence? Does the meaning change?

Hoy (today) is quite flexible in position. All of these are grammatical:

Hoy sí comprendo la lección.
Hoy comprendo la lección.
Yo sí comprendo la lección hoy.
Comprendo la lección hoy.

The basic meaning (“today I understand the lesson”) stays the same.
Word order mainly affects emphasis:

Hoy sí comprendo la lección.
Emphasizes today (maybe: I didn’t understand it before, but today I do).
Yo sí comprendo la lección hoy.
Emphasizes I (yo) and sí (I do), with hoy giving time info at the end.

Why is it comprendo and not comprende?

Because comprendo is the first-person singular form of comprender in the present tense.

Present tense of comprender:

yo comprendo – I understand
tú comprendes – you understand
él / ella / usted comprende – he/she/you (formal) understand(s)
nosotros comprendemos – we understand
ellos / ellas / ustedes comprenden – they / you all understand

So:

Yo comprendo = I understand
Él comprende = He understands

Is comprendo present simple or something like “I am understanding”? How do aspect and tense work here?

Comprendo is present simple in Spanish, but it often covers both:

English “I understand”
English “I am understanding” (when English uses progressive)

Spanish uses the progressive (estar + gerund) less often than English, and almost never with verbs like “understand”:

❌ Estoy comprendiendo la lección hoy (grammatical but odd in most contexts)
✅ Comprendo la lección hoy (normal)

So comprendo is the natural way to say “I understand / I am understanding” here.

Could I say Entendí la lección hoy instead of comprendo la lección hoy?

Yes, but the tense and meaning change:

Comprendo la lección hoy.
Present: I understand the lesson today (right now / at this point).
Entendí la lección hoy.
Preterite: I understood the lesson today (at some point earlier today, and that action is complete).

Use the present (comprendo / entiendo) when focusing on your current state of understanding.
Use the preterite (entendí / comprendí) to talk about when you came to understand it (a finished event earlier today).

How do you pronounce comprendo la lección? Where is the stress?

Basic pronunciation and stress:

comprendo → com–pren–do
Stress on pren.
la → just like English “la” in “la-la,” very short.
lección → lec–ción
Stress on ción. The cc is pronounced like k + s: approx. lek-syón.

So the main stressed syllables are pren and ción:
comPRENdo la lecCIÓN.

Could I say Yo sí la comprendo hoy instead of Yo sí comprendo la lección hoy?

Yes, that’s correct Spanish:

Yo sí la comprendo hoy.
= I do understand it today.

Here:

la is a direct object pronoun replacing la lección (feminine, singular).
Word order is: (subject) + sí + object pronoun + verb.

Both are fine:

Yo sí comprendo la lección hoy. (explicit noun)
Yo sí la comprendo hoy. (pronoun replacing a known noun)

You’d typically use la once “the lesson” is already clear from the context.