Abans de sortir, cal que llegim el cartell de l'entrada.

Yes, literally it is before of leaving / before to leave, but the natural English translation is before leaving or before we leave.

In Catalan, abans de + infinitive is a very common structure:

• abans de sortir = before leaving / before we leave
• abans de menjar = before eating
• abans de començar = before starting

So after abans de, Catalan normally uses an infinitive, where English often uses either a gerund (before leaving) or a full clause (before we leave).

Sortir usually means to go out, to leave, or to exit, depending on context.

Here, in Abans de sortir, it means something like:

• before leaving
• before going out
• before exiting

So the exact English choice depends on the situation, but the Catalan verb is the normal everyday verb for going out or leaving a place.

Cal is an impersonal verb that means it is necessary, one must, or it is needed.

So:

• cal = it is necessary
• cal que... = it is necessary that...

There is no normal subject because this is an impersonal construction, like:

• Cal estudiar. = It is necessary to study. / One must study.
• Cal que marxem. = We need to leave.

It is very common in Catalan and often sounds more natural than a heavier phrase like és necessari.

Because cal que introduces a subordinate clause.

Compare these two patterns:

• cal + infinitive

  • Cal llegir el cartell.
  • It’s necessary to read the sign.

• cal que + finite verb

  • Cal que llegim el cartell.
  • It’s necessary that we read the sign.

So que is needed because the second part has a conjugated verb (llegim) rather than an infinitive.

Because the sentence is saying that we read, not just to read.

Compare:

• Cal llegir el cartell. = It is necessary to read the sign.
• Cal que llegim el cartell. = It is necessary that we read the sign.

In your sentence, the speaker includes we, so Catalan uses a conjugated verb:

• llegim = we read

Also, after cal que, Catalan uses the subjunctive. For nosaltres, the present subjunctive form of llegir is also llegim, so it looks identical to the present indicative here.

Because cal que expresses necessity, and in Catalan, expressions of necessity, desire, doubt, emotion, and similar ideas often trigger the subjunctive.

So:

• Cal que llegim el cartell.
• És important que arribis d’hora.
• Vull que vinguis.

For a learner, the useful rule is:

cal que + subjunctive

In this sentence, llegim is the subjunctive form for nosaltres.

You know from the grammar of the sentence.

After cal que, Catalan requires the subjunctive, so even though llegim looks the same as the indicative we read, it is functioning as the subjunctive here.

This happens with some verbs in Catalan, especially in the nosaltres and vosaltres forms, where the present indicative and present subjunctive can be identical.

So the structure tells you the mood:

• cal que + verb → subjunctive

Yes, Abans de sortir, hem de llegir el cartell de l'entrada is also correct.

The difference is mainly one of style and focus:

• cal que llegim... = it is necessary that we read...
• hem de llegir... = we have to read...

Cal que sounds a bit more impersonal or general, while hem de sounds more direct and personal.

So:

• Cal que llegim el cartell. = It’s necessary for us to read the sign.
• Hem de llegir el cartell. = We have to read the sign.

Both are natural.

Because Catalan usually omits subject pronouns when the verb already makes the subject clear.

So:

• llegim already means we read
• nosaltres llegim is only used for emphasis, contrast, or clarity

For example:

• Cal que llegim el cartell. = neutral
• Cal que nosaltres llegim el cartell, no ells. = emphasis/contrast

This is very normal in Catalan, as in Spanish or Italian.

Cartell can mean sign, poster, or notice, depending on context.

In el cartell de l'entrada, the most natural English meaning is usually:

• the sign at the entrance or
• the notice at the entrance

If the context were advertising or public announcements, cartell could also mean poster.

So the word is broader than just one English equivalent.

It means of the entrance or, more naturally in English, at the entrance / by the entrance / for the entrance, depending on context.

Literally:

• de = of
• l'entrada = the entrance

So:

• el cartell de l'entrada = the entrance sign / the sign at the entrance

Catalan often uses de in places where English prefers a different preposition or a noun-noun structure.

Because la becomes l' before a vowel sound.

So:

• la porta = the door
• l'entrada = the entrance
• l'escola = the school

This is called elision. It is very common in Catalan.

And after de, you get:

• de + l'entrada = de l'entrada

It is very natural and usually preferred.

Abans de sortir is an introductory time expression, so Catalan commonly puts a comma after it:

• Abans de sortir, cal que llegim el cartell de l'entrada.

Without the comma, the sentence may still be understandable, but the comma makes the structure clearer and more natural in writing.

Yes, that is a very reasonable translation.

Depending on tone and context, cal que can come across in English as:

• we must
• we have to
• we need to
• we should

Strictly speaking, cal que expresses necessity, so need to or have to is often closest. But in natural English, should may fit if the tone is a bit softer.

So the exact English wording depends on context, even though the Catalan structure stays the same.