Learn Hardcore Spanish (Latin America): Hoy no entiendo nada en la clase. - Today I don't understand anything in class.

No goes before the verb: no entiendo (I don’t understand).
Nada is the negative word that means “nothing / anything” in this context: no entiendo nada.

This is called negative concord: the negatives “match” each other and together express a single negative idea.

So:

No entiendo nada = I don’t understand anything / I understand nothing.

Unlike in standard English, this is not “wrong grammar”; it’s the regular way to say it in Spanish.

What tense is entiendo, and why isn’t it estoy entendiendo?

Entiendo is the present indicative of entender.

In Spanish, the simple present is used a lot more than in English. It covers:

things that are generally true (Siempre entiendo – I always understand)
things happening right now (Hoy no entiendo – Today I don’t understand / I’m not understanding)

Estoy entendiendo (present progressive) is possible, but it sounds more like emphasizing the ongoing process, often when understanding is gradually improving:

Creo que ya estoy entendiendo – I think I’m starting to understand now.

For a simple complaint about today’s class, no entiendo is the most natural.

Why is there no yo in the sentence? Could I say Hoy yo no entiendo nada en la clase?

Spanish verb endings already show who the subject is, so the subject pronoun is usually optional.

Entiendo already implies yo (I).
Hoy no entiendo nada en la clase = I don’t understand anything in class today.

You can say Hoy yo no entiendo nada en la clase, but:

It sounds like you’re contrasting yourself with others:
- Hoy yo no entiendo nada en la clase, pero ellos sí entienden.
  (Today I don’t understand anything in class, but they do.)

Without that contrast, most native speakers would just leave out yo.

Is nada here “nothing” or “anything”? In English I’d say I don’t understand anything.

Literally, nada means nothing. But when it’s used with no before the verb (no entiendo nada), the most natural English translation is often with anything:

No entiendo nada = I don’t understand anything / I understand nothing.

English negation usually uses don’t + anything; Spanish prefers no + verb + nada.

So:

Hoy no entiendo nada en la clase.
- Best everyday English: I don’t understand anything in class today.

What’s the difference between entender and comprender here? Could I say Hoy no comprendo nada en la clase?

You can say Hoy no comprendo nada en la clase, and it’s grammatically correct.

In modern everyday Spanish (especially in Latin America):

Entender is more common and a bit more colloquial / neutral.
Comprender can sound a little more formal, or like “to fully grasp / to comprehend”.

Often they’re used interchangeably, especially in sentences like this. For an everyday comment about class, most people would naturally say:

Hoy no entiendo nada en la clase.

Why is it en la clase and not a la clase or de la clase?

The choice depends on the idea you want to express:

En la clase = in class / during class (location or situation)
- Hoy no entiendo nada en la clase.
  → While I’m in class today, I don’t understand anything.
A la clase usually means to the class (movement toward):
- Voy a la clase. – I’m going to class.
De la clase is more like of the class / about the class:
- No entiendo nada de la clase. – I don’t understand anything about the class / the material.

In your sentence, you’re talking about what happens while you’re there, so en la clase is the natural preposition.

Is clase always feminine? Why la clase and not el clase?

Yes, clase is a feminine noun, so it always takes feminine articles and adjectives:

la clase (the class)
esta clase (this class)
una clase interesante (an interesting class)

In Spanish, grammatical gender is mostly a property of each noun, not something you can choose freely. Some patterns help (like many nouns ending in -a are feminine), but clase just has to be memorized as feminine.

So el clase is incorrect; it must be la clase.

Could I drop la and just say en clase?

Yes. Both are used, and both are correct:

Hoy no entiendo nada en clase.
Hoy no entiendo nada en la clase.

Often:

En clase feels a bit more general (“in class” as an activity/situation).
En la clase can sound slightly more specific, referring to a particular class (e.g., today’s math class).

In real speech, the difference is subtle, and many speakers use them almost interchangeably in this context.

Could I say Hoy no entiendo nada de la clase instead of en la clase? Does that change the meaning?

You can, and it changes the focus slightly:

Hoy no entiendo nada en la clase.
- Focus on what happens while you’re in class today (during the lesson, in that setting).
Hoy no entiendo nada de la clase.
- Focus more on the content of the class: the lesson, the subject matter.
- Similar to I don’t understand anything from the class / about the class today.

Both work; the original en la clase is what you’d typically say when talking about your experience while you are in class.

Can the word order change? For example, are these correct: Hoy en la clase no entiendo nada or No entiendo nada hoy en la clase?

Yes, Spanish word order is fairly flexible, and these versions are all possible:

Hoy no entiendo nada en la clase.
Hoy en la clase no entiendo nada.
En la clase hoy no entiendo nada.
No entiendo nada hoy en la clase.

They all mean essentially the same thing.
Minor differences:

Putting hoy first (Hoy…) is common and puts emphasis on “today”.
Moving en la clase earlier highlights the place a bit more.

But in everyday speech, none of these sound strange; the original is very natural.

How would I say “I never understand anything in class”? Is nunca used like no … nada?

To say I never understand anything in class, you’d usually say:

Nunca entiendo nada en la clase.

Or, with no:

No entiendo nada nunca en la clase. (less common, more emphatic)

With nunca, you have two main patterns:

Nunca before the verb (then you don’t need no):
- Nunca entiendo. – I never understand.
No before the verb and nunca after (double negative / concord):
- No entiendo nunca. – I never understand.

Both are correct; Nunca entiendo nada en la clase is the simplest and most natural here.

How is Hoy no entiendo nada en la clase pronounced in Latin American Spanish? Anything tricky?

Main points for Latin American pronunciation:

Hoy:
- h is silent.
- Pronounced like oy in English boy but without the b: [oi].
no:
- Like English no, but shorter and cleaner.
entiendo:
- en–TIEN–do → stress on TIEN.
- ie is one sound, like English yet but glided: [jen] or [ʝen].
nada:
- NA–da → stress on NA.
- d between vowels is soft, like a light th in this in many accents.
en la clase:
- clase: CLA–se → stress on CLA; c before a is a hard k sound: [ˈklase].
- In Latin America, c before e/i is pronounced like s, but here it’s before a, so it’s k.

Full sentence (rough guide):

Hoy no entiendo nada en la clase →
[oi no enˈtjen̪do ˈnaða en la ˈklase] (approximate Latin American pronunciation).

Are there more casual or slangy ways to say this in Latin America?

Yes, in informal speech people might use more colloquial verbs or add emphasis. Examples (very informal, vary by country):

Hoy no agarro nada en clase.
- Used in some countries (e.g., parts of Mexico); agarrar here = to get / to catch (an idea).
Hoy no cacho nada en la clase.
- In some regions (e.g., Chile), cachar = to get / to understand (slang).
Hoy no estoy entendiendo nada.
- Still standard, but sounds more like “I’m just not getting anything today” (emphasizing the process).

Your original sentence Hoy no entiendo nada en la clase is neutral, correct, and widely understood everywhere in Latin America.