No crec que la meva filla pugui parlar gaire, perquè li fa mal el nas i no para d'esternudar; per això sempre porta un mocador.

Because after crec que in the negative—no crec que—Catalan normally uses the subjunctive in the following clause.

• No crec que ... pugui = I don’t think ... can
• Crec que ... pot = I think ... can

So:

• No crec que la meva filla pugui parlar gaire is the natural Catalan pattern.
• Using pot here would sound ungrammatical or at least very nonstandard in normal usage.

This is one of the most important Catalan subjunctive triggers to learn:

• crec que
  • indicative
• no crec que
  • subjunctive

pugui is the present subjunctive of poder (to be able to / can), for ell/ella/vostè.

Here is the relevant contrast:

• pot = present indicative
• pugui = present subjunctive

So:

• La meva filla pot parlar = My daughter can speak/talk
• No crec que la meva filla pugui parlar = I don’t think my daughter can speak/talk

Catalan usually uses the definite article with possessives:

• la meva filla = my daughter
• el meu pare = my father
• la nostra casa = our house

That is completely normal Catalan. English does not use an article there, but Catalan usually does.

So la meva filla is not the my daughter in meaning—it simply means my daughter.

In this sentence, gaire means much / very much and is used because the sentence is negative:

• No ... gaire = not much / not very much

So:

• No crec que la meva filla pugui parlar gaire = I don’t think my daughter can talk much

Catalan often uses gaire in negative contexts, while molt is more typical in affirmative ones:

• Parla molt = She talks a lot
• No parla gaire = She doesn’t talk much

That contrast is very common and worth memorizing.

It can mean either, depending on context. In this sentence, talk is probably the most natural English choice:

• parlar gaire = talk much

But speak much is not wrong.

Catalan parlar covers a range that overlaps with both English speak and talk.

That is exactly the kind of structure Catalan often uses for body parts and physical discomfort.

• li = to her
• fa mal = hurts / causes pain
• el nas = the nose

So literally, it is something like:

• her nose is causing her pain
• or the nose hurts to her

But the natural English translation is:

• her nose hurts
• or she has a sore nose

Catalan commonly uses this pattern:

• Em fa mal el cap = My head hurts
• Li fa mal la gola = Her throat hurts
• Ens fan mal els peus = Our feet hurt

With body parts, Catalan usually prefers:

• an indirect object pronoun to show whose body it is
• plus the definite article on the body part

So instead of saying her nose, Catalan usually says the equivalent of to her, the nose:

• li fa mal el nas

This is more natural than el seu nas in ordinary contexts.

Using el seu nas is possible, but it usually sounds more emphatic, contrastive, or less idiomatic in simple everyday sentences.

Fer mal literally means to do harm / to cause pain, but in everyday Catalan it is very often used as to hurt.

Examples:

• Em fa mal el cap = My head hurts
• Això fa mal = That hurts
• Li fan mal les cames = Her legs hurt

So in your sentence:

• li fa mal el nas = her nose hurts

It means she can’t stop sneezing or she keeps sneezing.

The construction is:

• parar de + infinitive = to stop doing something

So in the negative:

• no para de + infinitive = doesn’t stop doing something
• very naturally in English: keeps + -ing

Examples:

• No para de parlar = He keeps talking
• No para de plorar = She won’t stop crying
• No para d'esternudar = She can’t stop sneezing / She keeps sneezing

Because de is shortened before a vowel:

• de + esternudar → d'esternudar

This is a normal Catalan contraction/apostrophe rule.

So:

• parar d'esternudar not
• parar de esternudar

Esternudar means to sneeze.

So:

• esternuda = he/she sneezes
• esternudar = to sneeze
• no para d'esternudar = keeps sneezing

A related noun is:

• un esternut = a sneeze

Because perquè means because.

This is important because Catalan distinguishes several similar-looking forms:

• perquè = because
• per què = why / for what reason
• per a què = what for / for what purpose (in many contexts)

In your sentence:

• perquè li fa mal el nas... = because her nose hurts...

So this is the conjunction because, written perquè.

Per això means for that reason, that’s why, or therefore.

In the sentence:

• ...; per això sempre porta un mocador.
• ...; that’s why she always carries a handkerchief.

It connects the cause and the result:

• she has a sore nose and keeps sneezing
• therefore / that’s why she always carries a handkerchief

The semicolon links two closely related parts of the sentence:

1. the explanation of the problem
   
   • li fa mal el nas i no para d'esternudar
2. the consequence
   
   • per això sempre porta un mocador

It works a bit like a strong comma or a softer full stop. It is not a grammar point unique to Catalan, but it is a natural punctuation choice here.

A comma or full stop could also be possible depending on style, but the semicolon is perfectly good.

Because un mocador means a handkerchief in a general sense: she carries one, not necessarily a specific previously identified handkerchief.

• porta un mocador = she carries a handkerchief
• porta el mocador = she is carrying the handkerchief / the handkerchief

The indefinite article un is natural here because the sentence is just saying that carrying a handkerchief is her usual habit.

Here mocador means handkerchief.

In other contexts, mocador can also mean a scarf or headscarf, depending on usage and region. But in this sentence, because of the sneezing and sore nose, the meaning is clearly handkerchief.

Sempre means always, and putting it before the verb is very normal Catalan word order:

• sempre porta un mocador = she always carries a handkerchief

Catalan adverbs like sempre, mai, sovint, and ja are often placed before the verb, though word order can vary depending on emphasis.

So this word order is standard and natural.

Yes. A fairly literal translation is:

• I don’t think that my daughter can talk/speak much, because her nose hurts and she can’t stop sneezing; that’s why she always carries a handkerchief.

The main things that are less literal under the surface are:

• pugui because Catalan uses the subjunctive after no crec que
• li fa mal el nas because Catalan uses the indirect-object + body-part pattern
• no para d'esternudar because Catalan uses not stop + infinitive where English often prefers keep + -ing or can’t stop + -ing

So the overall meaning is straightforward, even though some grammar patterns differ from English.