Quan tinc mal al nas, no respiro gaire bé.

Quan means when and introduces a time clause:

• Quan tinc mal al nas = When my nose hurts / When I have pain in my nose

It is followed here by the present tense because Catalan often uses the present for general situations or repeated facts:

• Quan plou, em quedo a casa. = When it rains, I stay home.
• Quan tinc son, me'n vaig a dormir. = When I'm sleepy, I go to sleep.

So the sentence describes something that generally happens whenever that condition is true.

Catalan very often uses tenir mal literally to have pain rather than a direct equivalent of English to hurt.

So:

• Tinc mal = I have pain / It hurts
• Tinc mal al nas = My nose hurts / I have pain in my nose

This is a very common pattern with body parts:

• Tinc mal al cap. = My head hurts.
• Tinc mal a l'esquena. = My back hurts.
• Tinc mal a la cama. = My leg hurts.

English uses hurt, but Catalan often prefers tenir mal.

Al is the contraction of:

• a + el = al

So:

• mal al nas = pain in/to the nose area

This is just normal Catalan contraction, like:

• Vaig al mercat. = I go to the market.
• Dona-ho al noi. = Give it to the boy.

Because nas is masculine singular and takes el, a el nas becomes al nas.

Catalan normally uses the definite article with body parts:

• el nas = the nose
• la mà = the hand
• els ulls = the eyes

So the natural expression is:

• mal al nas not
• mal a nas

This differs from English, which often uses a possessive:

• my nose hurts

Catalan often does not need the possessive when it is obvious whose body part is meant.

Because Catalan usually avoids possessives with body parts when the owner is already clear from the context.

So instead of saying:

• Tinc mal al meu nas

Catalan normally says:

• Tinc mal al nas

The my is understood because the verb is tinc (I have). This is very common:

• Em rento les mans. = I wash my hands.
  Literally: I wash the hands to myself.
• M'he fet mal al braç. = I hurt my arm.

Using meu/meva is possible in some contexts, but it is usually unnecessary here.

No. Catalan has a few pain expressions, and learners often notice that.

For example:

• tenir mal al nas = pain in the nose / the nose hurts
• tenir mal de cap = to have a headache

With some body-related pains, Catalan commonly uses mal de; in other cases, especially when talking about a specific place on the body, mal a/al/a la is very natural.

So mal al nas sounds like pain located in the nose. A learner should mainly remember the whole expression tenir mal a/al/a la + body part as a useful pattern.

Here gaire means very or much, but it usually appears in negative, question, or similar environments.

So:

• no respiro gaire bé = I don't breathe very well

A very useful thing to remember is:

• gaire often goes with no
• molt is the normal word in affirmative sentences

Compare:

• No menjo gaire. = I don't eat much.
• Menjo molt. = I eat a lot.

And here:

• No respiro gaire bé. = I don't breathe very well.
• Respiro molt bé. = I breathe very well.

Because in standard Catalan, gaire is the natural choice after a negative:

• no ... gaire = not very / not much

So:

• No respiro gaire bé = natural
• No respiro molt bé = less idiomatic in this meaning

Think of it like this:

• molt bé = very well
• no gaire bé = not very well

That is why gaire fits perfectly here.

Because Catalan is a pro-drop language, which means subject pronouns are often omitted when the verb ending already shows who the subject is.

Here:

• tinc already means I have
• respiro already means I breathe

So jo is not necessary:

• Quan tinc mal al nas, no respiro gaire bé.

You could add jo for emphasis:

• Quan tinc mal al nas, jo no respiro gaire bé.

But in a neutral sentence, leaving it out is more natural.

Because the sentence expresses a general truth or repeated situation:

• When I have pain in my nose, I don't breathe very well.

Catalan often uses the present tense for this kind of meaning, just like English can do:

• When I eat too fast, I feel sick.
• Quan menjo massa de pressa, em trobo malament.

So the present tense here does not only mean right now. It can also mean whenever this happens.

Yes. That would mean:

• No puc respirar gaire bé = I can't breathe very well

This puts more emphasis on ability or difficulty. By contrast:

• No respiro gaire bé = I don't breathe very well

In many situations, both are possible, but the nuance is slightly different:

• no respiro gaire bé = my breathing is poor
• no puc respirar gaire bé = I am not able to breathe well

The sentence you were given is perfectly natural, but no puc respirar gaire bé is also a very useful expression.

Bé means well. It is the adverb form.

So:

• respiro bé = I breathe well
• no respiro gaire bé = I don't breathe very well

A quick comparison:

• bo / bona = good (adjective)
• bé = well (adverb)

Examples:

• És un bon metge. = He is a good doctor.
• Respira bé. = He breathes well.

So in this sentence, bé modifies the verb respiro.

The comma is natural because the sentence begins with a subordinate clause:

• Quan tinc mal al nas, ...
• When my nose hurts, ...

This is similar to English, where a comma is also common after an introductory when clause.

You may sometimes see punctuation used a bit flexibly in informal writing, but with this sentence the comma is standard and helpful.

A simple learner-friendly approximation is:

• gaire ≈ GUY-ruh or GAI-ruh

The exact pronunciation depends somewhat on accent, but the important thing is:

• the g is a hard g
• the word has two syllables
• the final e is not strongly pronounced like English ee

If you are aiming for standard Central Catalan pronunciation, it is roughly /ˈɡaj.ɾə/.

Yes. Tinc mal al nas is broad and can mean that your nose hurts or is painful, without specifying why.

Depending on context, it could be because of:

• a cold
• irritation
• dryness
• injury
• congestion

The second part, no respiro gaire bé, suggests that the nose pain is affecting breathing, so many people would naturally imagine congestion or irritation, but the sentence itself does not state the exact cause.