Learn Hardcore Spanish (Latin America): Mi amiga sí aguanta las películas de terror; yo no. - My friend can put up with horror movies; I can't.

Mi amiga aguanta las películas de terror.
→ My friend can handle horror movies. (neutral statement)
Mi amiga sí aguanta las películas de terror.
→ My friend *does handle/can actually handle horror movies.* (contrasting or emphasizing)

The sí emphasizes that she indeed can handle them, often implying contrast with someone else (here: yo no – I don’t). It’s like stressing does in English:
“My friend does handle horror movies; I don’t.”

What exactly does aguantar mean here?

Aguantar is a very common verb in Spanish with several related meanings:

to tolerate / to stand / to put up with
to endure / to withstand
to handle

In this context, aguantar las películas de terror means:

to be able to tolerate horror movies
to handle/get through horror movies without freaking out too much

So the idea is not that she likes them, just that she can stand them. It’s similar to English:

I can’t stand horror movies. → No aguanto las películas de terror.

Why is it aguanta and not something like puede aguantar or le gustan?

Each option has a different nuance:

Mi amiga aguanta las películas de terror.
→ She can tolerate them; they don’t overwhelm her.
Mi amiga puede aguantar las películas de terror.
→ She is able to tolerate them (more literal “can”). This is fine, but often feels wordier than necessary; aguanta already implies that ability.
A mi amiga le gustan las películas de terror.
→ She likes horror movies.
This is a different idea. The original sentence is about tolerance, not enjoyment.

So aguanta is chosen to stress endurance/tolerance, not liking.

Why is it las películas de terror and not just películas de terror?

Spanish uses the definite article (el, la, los, las) more than English:

las películas de terror
literally: the horror movies
functionally: horror movies (in general)

Here, las is not pointing to specific movies, but to that whole category of movies. In Spanish, it’s very natural to say:

Odio las matemáticas. → I hate math.
Me encantan los perros. → I love dogs.
No aguanto las películas de terror. → I can’t stand horror movies.

You could say aguanta películas de terror (without las), but it would sound more incomplete or less natural in this generic “type of thing” sense.

Why is it de terror and not something like de miedo? Are there differences?

Both are used, but there are nuances and regional tendencies:

películas de terror
Very common, sounds a bit more formal/neutral. Literally “terror films.”
películas de miedo
Also common, often a bit more colloquial or used in everyday speech. Literally “scary movies.”

In Latin America, películas de terror is extremely standard and widely understood. Películas de miedo is also understood and used, but if you want a very neutral, textbook-style phrase, películas de terror is perfect.

Why is there a semicolon (;) before yo no? Could you say it differently?

The semicolon connects two related but complete ideas:

Mi amiga sí aguanta las películas de terror; yo no.
My friend can handle horror movies; I can’t.

You could also write or say:

Mi amiga sí aguanta las películas de terror, pero yo no.
(…but I don’t.)

In speech, most people would simply use pero and a comma. The version with a semicolon is more about writing style; the core grammar of yo no (subject + negation) is the same.

Why do we say yo no and not something longer like yo no aguanto?

Spanish often omits repeated verbs when they’re understood from context:

Mi amiga sí aguanta las películas de terror; yo no.
(Full idea: yo no aguanto las películas de terror.)

Since aguanta just appeared, it doesn’t need to be repeated. English does the same sometimes:

My friend likes horror movies; I don’t.

If you say yo no aguanto, it’s still correct, just a bit more explicit and longer. In conversation, the shorter yo no is very natural.

Is the subject pronoun yo necessary here? Could you say just no?

You need something there; no by itself would be too bare:

Mi amiga sí aguanta las películas de terror; yo no. ✅
Mi amiga sí aguanta las películas de terror; no. ❌ (sounds incomplete/odd)

Options that work:

…; yo no. (most natural, clear contrast)
…; no, yo no. (more conversational, like answering someone)
…; pero yo no. (adds “but,” same meaning)

Leaving out yo here would remove the clear contrast between mi amiga and yo. The pronoun is important for the emphasis: She does, but I don’t.

Why is it amiga and not amigo? Does it always have to match the person’s gender?

Yes, amiga is the feminine form of “friend,” and amigo is the masculine form.

Mi amiga → my (female) friend
Mi amigo → my (male) friend

Spanish nouns referring to people usually agree in gender with the person:

el profesor / la profesora (male/female teacher)
el vecino / la vecina (male/female neighbor)

So mi amiga tells us the friend is female. If the friend were male, the sentence would be:

Mi amigo sí aguanta las películas de terror; yo no.

Could I leave out sí and just say Mi amiga aguanta las películas de terror; yo no? What changes?

Yes, that’s grammatically fine:

Mi amiga aguanta las películas de terror; yo no.
→ Simple statement of fact.
Mi amiga sí aguanta las películas de terror; yo no.
→ Adds contrast/emphasis: She actually does; I don’t.

The version with sí sounds more like you’re:

responding to an implied doubt:
“She really can handle them.”
clearly contrasting:
“She can handle them, but I definitely can’t.”

Without sí, it’s neutral description; with sí, it’s more emphatic and contrastive.

Is aguantar informal? Are there more “polite” or neutral alternatives?

Aguantar is very common and perfectly fine in everyday speech. It’s not rude, but it can sound a bit colloquial in some contexts.

Alternatives with slightly different nuances:

Mi amiga soporta las películas de terror.
→ Soporta is a bit more neutral/formal: to bear/endure.
Mi amiga tolera las películas de terror.
→ Tolerates (sounds more formal/technical, like in English).
Mi amiga puede ver películas de terror.
→ She can watch horror movies (focuses more on ability to watch them, not on emotional tolerance).

For everyday Latin American conversation, aguantar is very natural and widely used.