Si no hi ha cereals, la meva filla en compra després de la classe.

Hi ha is the standard Catalan way to say there is / there are.

• ha by itself is just the verb form has from haver, but in this existential meaning Catalan normally uses hi ha
• està means is located / is situated / is in a state, not there is

So:

• Hi ha cereals = There are cereals
• Els cereals estan a l’armari = The cereals are in the cupboard

In your sentence, the meaning is existential: it is talking about whether cereals are available, so hi ha is the correct choice.

In hi ha, hi is part of a fixed expression. Historically it relates to location, but for learners it is best to treat hi ha as a whole unit meaning there is / there are.

So you should learn:

• hi ha = there is / there are
• no hi ha = there isn’t / there aren’t

Examples:

• Hi ha pa = There is bread
• No hi ha llet = There isn’t any milk
• Hi ha estudiants = There are students

Even though hi has other uses in Catalan, in hi ha it is easiest to understand it as a required part of the expression.

Catalan often omits the article when speaking in a general, indefinite sense about things, especially after hi ha.

So:

• Si no hi ha cereals = If there are no cereals / if there isn’t any cereal

This does not mean specific cereals already identified; it means cereals in general, as a food item or supply.

Compare:

• No hi ha cereals = There are no cereals
• No hi ha els cereals que volia = The cereals I wanted aren’t there

The second one is specific, so it uses the article.

Here en is a pronoun that replaces cereals. It means something like some, any, or of them, depending on the context.

So instead of repeating cereals, Catalan uses en:

• Si no hi ha cereals, la meva filla en compra...
• literally: If there aren’t cereals, my daughter buys some...

This is very common in Catalan. The pronoun en is used when referring back to an indefinite quantity or to something introduced without a definite article.

More examples:

• No hi ha pa? En compro. = There isn’t any bread? I’ll buy some.
• Vols pomes? N’he comprat. = Do you want apples? I bought some.

Yes, you could, but it changes the style slightly.

• la meva filla compra cereals repeats the noun
• la meva filla en compra avoids repetition and sounds more natural in connected speech

Since cereals has just been mentioned in the first clause, Catalan often prefers the pronoun en in the second clause.

So both are possible, but en compra is usually better style here.

Because en is a weak pronoun, and in Catalan these pronouns usually come before a conjugated verb.

So:

• en compra
• els veu
• li parla

Not:

• compra en in this kind of sentence

With infinitives, imperatives, and some other structures, pronoun placement can be different, but with a normal present-tense verb like compra, the pronoun goes before it.

Because the subject is la meva filla, which is singular.

• la meva filla compra = my daughter buys
• les meves filles compren = my daughters buy

The pronoun en does not affect verb agreement. The verb agrees with the subject, not with the thing being bought.

So even though cereals is plural, the verb is singular because my daughter is singular.

Catalan normally uses the definite article with possessives:

• el meu pare
• la meva filla
• els seus amics

This is one of the big differences from English, where you normally just say my daughter, not the my daughter.

So in Catalan:

• la meva filla is the normal form

There are some exceptions, especially in certain family terms used in direct address or in some fixed expressions, but for most learners the safest rule is:

Use the article with possessives.

Because després is followed by the preposition de when it introduces a noun phrase.

So:

• després de la classe = after class
• després del dinar = after lunch
• després de la reunió = after the meeting

This is just the normal pattern in Catalan.

You can think of it as:

• després de + noun

Catalan often uses the article in places where English does not.

So English says:

• after class

But Catalan says:

• després de la classe

This is very common. Catalan tends to use the article with many nouns referring to everyday activities, institutions, or familiar contexts where English often leaves it out.

Because Catalan commonly uses the present indicative after si for real or likely conditions.

So:

• Si no hi ha cereals, la meva filla en compra...
• literally: If there are no cereals, my daughter buys some...

Depending on context, this can express a habitual action or a normal consequence.

Catalan does not usually use the future tense directly after si in this kind of clause.

So Catalan prefers:

• Si no hi ha cereals, en comprarà després. = If there are no cereals, she will buy some later.

Not normally:

• Si no hi haurà cereals... for this meaning

This is similar to English, which also usually says If there are no cereals..., not If there will be no cereals...

No. They are different words.

• si = if
• sí = yes

In your sentence, it is si without an accent because it means if.

Examples:

• Si plou, no surto. = If it rains, I’m not going out.
• Sí, d’acord. = Yes, okay.

This accent difference is important in writing.

With the present tense, it most naturally sounds habitual or generally true:

• If there are no cereals, my daughter buys some after class

That sounds like a routine or usual solution.

If you wanted to make it more clearly about a future specific case, Catalan would often keep the si clause in the present but use a future or another future-oriented form in the main clause:

• Si no hi ha cereals, la meva filla en comprarà després de la classe.

So the original sentence is especially natural if you mean something like a repeated pattern or household habit.