Si s'acaba el paper, no puc imprimir el document.

Because acabar-se is a very common pronominal form in Catalan meaning to run out / to come to an end / to get used up.

So:

• acabar = to finish, to end something, or to finish doing something
• acabar-se = to be finished, to run out, to come to an end

In this sentence, s'acaba el paper means that the paper supply runs out or gets used up.

Compare:

• Acabo el document = I finish the document
• S'acaba el paper = The paper runs out

The s' is the shortened form of es before a vowel.

It is the unstressed pronoun es, which becomes s' before a vowel.

So:

• es acaba becomes
• s'acaba

This shortening is just for pronunciation and spelling. Catalan often drops the vowel of short pronouns before another vowel.

Other examples:

• s'obre = es obre
• s'acosta = es acosta

Because si without an accent means if.

Catalan distinguishes:

• si = if
• sí = yes

So in this sentence, Si s'acaba el paper... introduces a condition: If the paper runs out...

Catalan often uses the present tense in real or likely conditions, especially for general situations or immediate practical consequences.

So Si s'acaba el paper, no puc imprimir el document is natural Catalan.

It can sound like:

• a general truth
• an immediate situation
• a practical rule

If the speaker wants to sound more clearly future-oriented, they could also say:

• Si s'acaba el paper, no podré imprimir el document = If the paper runs out, I won't be able to print the document

So no puc here is not wrong at all; it can mean I can't print the document in that situation.

Yes. Puc is the 1st person singular form of poder, meaning to be able to / can.

Present tense of poder:

• jo puc
• tu pots
• ell/ella pot
• nosaltres podem
• vosaltres podeu
• ells/elles poden

So:

• no puc imprimir = I can't print

It is irregular, so it does not follow a simple pattern like regular -er verbs.

Because after poder, Catalan uses a bare infinitive, just like English after can.

So:

• puc imprimir
• pots venir
• podem sortir

Not:

• puc a imprimir

This is similar to English:

• I can print not
• I can to print

Catalan uses the definite article more often than English does.

Here el paper means the paper, but in context it can refer to the paper in the printer, the available paper supply, or paper in general as a known thing in the situation.

Catalan often includes the article where English may omit it. So a native English speaker may expect just paper, but el paper is very natural in Catalan.

For the same reason: Catalan usually uses the definite article with a specific noun that is understood in context.

Here el document means a specific document the speaker wants to print.

So:

• imprimir el document = print the document

Using el makes it sound like a known, identifiable document, not just any document.

In this sentence, el paper most naturally means the paper available for printing, so effectively the printer paper or the paper supply.

Catalan often relies on context for this. Since the next part is no puc imprimir el document, the listener naturally understands that this is about paper needed for the printer.

In Catalan, the normal negative marker is no, and it goes before the conjugated verb.

So:

• no puc imprimir = I can't print
• no tinc paper = I don't have paper
• no vull esperar = I don't want to wait

This is the standard position for negation.

Not with exactly the same meaning.

• si = if
• quan = when

So:

• Si s'acaba el paper... = If the paper runs out...
• Quan s'acaba el paper... = When the paper runs out...

Using si presents it as a condition. Using quan presents it more as something expected to happen.

In many real situations, si is the better choice because running out of paper is a possibility, not necessarily a certainty.

Not really. That literal idea may help you see the grammar, but it is not how the expression works in real usage.

The pronominal form acabar-se is just how Catalan commonly expresses the idea that something runs out or comes to an end.

So the natural interpretation is:

• s'acaba el paper = the paper runs out / the paper is used up

It is better to learn acabar-se as a normal expression, not as a truly reflexive action.

It can be understood either way, depending on context.

It may mean a general practical fact:

• Whenever the paper runs out, I can't print the document.

Or it may refer to the current situation:

• If the paper runs out now, I can't print the document.

Catalan present tense is flexible enough to allow both readings. If the speaker wants to be more clearly future-specific, they might say:

• Si s'acaba el paper, no podré imprimir el document

But the original sentence is completely natural.