A la meva amiga li fa mal la panxa perquè avui no ha dinat.

Yes, they refer to the same person.

In Catalan, this is very common with indirect objects: you often have both:

• the full phrase: A la meva amiga
• the clitic pronoun: li

This is called clitic doubling.

So:

• A la meva amiga = to my friend
• li = to her

In this sentence, li is not optional in normal Catalan. Once you introduce the indirect object like A la meva amiga, the pronoun li is expected.

A similar pattern is:

• A en Joan li agrada el cafè. = Joan likes coffee.

Because Catalan normally uses the definite article with possessives.

So the usual pattern is:

• la meva amiga = my friend
• el meu llibre = my book
• la seva casa = his/her house

This is different from English, where you usually use just my, your, his, etc. without the.

So la meva amiga is the normal Catalan way to say my friend.

This is a very common Catalan structure.

• fer mal = to hurt / to cause pain
• li = to her
• la panxa = the belly / tummy / stomach area

Literally, the structure is closer to:

• The belly causes pain to her

Natural English is:

• Her stomach hurts
• She has a stomachache

So the thing that hurts, la panxa, is the grammatical subject.

That is why the verb agrees with la panxa.

Because with body parts, Catalan usually uses the definite article, not a possessive, when it is already clear whose body part it is.

So Catalan prefers:

• Li fa mal la panxa. = Her stomach hurts.
• Em fa mal el cap. = My head hurts.
• Li fan mal les cames. = Her legs hurt.

The owner is already understood from the pronoun:

• em = to me
• et = to you
• li = to him/her

Using la seva panxa is possible, but it sounds more emphatic or contrastive, as if you really want to stress her stomach rather than someone else’s.

Not exactly.

Panxa is an everyday word meaning something like:

• belly
• tummy
• stomach area

It is common in normal speech.

Estómac is more anatomical and specifically means stomach as an internal organ.

So in a sentence about feeling pain after not eating, panxa sounds very natural and everyday.

Because the subject is singular: la panxa.

In li fa mal la panxa:

• la panxa = subject
• fa = singular verb form

If the thing that hurts is plural, the verb becomes plural:

• Li fan mal els peus. = Her feet hurt.
• Em fan mal les mans. = My hands hurt.

Notice that mal stays the same:

• fa mal
• fan mal

It does not change for singular or plural.

No. This is a very common false friend for English speakers.

In Catalan:

• esmorzar = to have breakfast
• dinar = to have lunch
• sopar = to have dinner / supper

So:

• avui no ha dinat = today she hasn’t had lunch

Even though dinar looks a bit like English dine, it refers to lunch, not dinner.

Ha dinat is the present perfect:

• ha = has
• dinat = had lunch

So no ha dinat means hasn’t had lunch.

This form is very natural here because:

• the time is avui = today
• the result matters now: she has a stomachache now because she hasn’t eaten lunch today

So the sentence has a clear connection to the present.

A different past form, like no va dinar, is possible in Catalan in other contexts, but no ha dinat fits very well here because of the current relevance.

Because perquè means because.

Catalan distinguishes:

• perquè = because
• per què = why / for what reason

So here:

• perquè avui no ha dinat = because today she hasn’t had lunch

The accent helps distinguish it from other similar forms.

Catalan word order is flexible, but not random.

This sentence begins with A la meva amiga to introduce the person as the topic:

• A la meva amiga li fa mal la panxa...

That is a very natural order.

You could also hear:

• Li fa mal la panxa a la meva amiga.

But if you start with the full indirect object phrase A la meva amiga, the pronoun li should still be there.

So the given sentence is both grammatical and very natural.

Yes. A very common alternative is:

• La meva amiga té mal de panxa perquè avui no ha dinat.

This also means:

• My friend has a stomachache because she hasn’t had lunch today.

So Catalan often expresses this idea in two common ways:

• Li fa mal la panxa = her stomach hurts
• Té mal de panxa = she has a stomachache

Both are natural, but the original sentence is perfectly normal Catalan.