Si l'adreça és correcta, Correus lliurarà el paquet demà.

Because adreça is a feminine singular noun, so it normally takes the article la: la adreça would be awkward in Catalan, so la contracts to l' before a vowel.

• la + adreça → l'adreça
• This is similar to:
  • l'escola
  • l'oficina
  • l'amiga

So l'adreça means the address.

Si means if.

It introduces a condition:

• Si l'adreça és correcta... = If the address is correct...

This is a very common structure in Catalan, just like in English:

• Si plou, no sortirem. = If it rains, we won’t go out.

Be careful not to confuse this si with other similar-looking words:

• sí with an accent = yes
• si without an accent = if

És is the 3rd person singular of the verb ser (to be), meaning is.

• és = is
• es without an accent is a different word, often a reflexive pronoun, like himself/herself/itself or part of a passive/reflexive construction.

So the accent matters a lot:

• L'adreça és correcta. = The address is correct.
• es would not work here

In short, és must have the accent because it is the verb form is.

Because correcta agrees with adreça, which is a feminine singular noun.

In Catalan, adjectives usually agree in gender and number with the noun they describe:

• adreça = feminine singular
• so: correcta = feminine singular

Compare:

• l'adreça correcta = the correct address
• el número correcte = the correct number
• les adreces correctes = the correct addresses

Even though here correcta comes after the verb és, it still agrees with adreça:

• L'adreça és correcta.

Correus is the name of the Spanish postal service, similar to saying the post office or Spain’s postal service.

In this sentence, it is treated as the subject:

• Correus lliurarà el paquet demà.
• Correus = the postal service
• lliurarà = will deliver

So this is like saying:

• Correus will deliver the package tomorrow.

Because it is a proper name, it does not need an article here.

Because the sentence refers to something that will happen tomorrow.

Lliurarà is the future tense of lliurar (to deliver):

• lliuraré = I will deliver
• lliuraràs = you will deliver
• lliurarà = he/she/it will deliver

Since the subject is Correus (treated as singular), the sentence uses lliurarà:

• Correus lliurarà el paquet demà.
• The postal service will deliver the package tomorrow.

The ending -à is typical for many future tense forms in the he/she/it person.

The accent helps mark the correct stress and distinguishes the form clearly.

In lliurarà, the stress falls on the last syllable:

• lli-u-ra-rà

This is the normal written form of the future tense here:

• lliurarà = will deliver

Catalan uses accents partly to show pronunciation, so it is important to write them correctly.

Yes, in many contexts entregarà would also be understood as will deliver.

However, lliurar is a very natural choice for deliveries, parcels, and formal/logistical contexts. So:

• Correus lliurarà el paquet demà. = very natural
• Correus entregarà el paquet demà. = also understandable, and often used

Learners should know that both verbs can overlap, but lliurar is especially common for handing over or delivering items.

The comma separates the if-clause from the main clause:

• Si l'adreça és correcta, = condition
• Correus lliurarà el paquet demà. = main result

This is similar to English:

• If the address is correct, the postal service will deliver the package tomorrow.

In Catalan, using a comma after an introductory conditional clause like this is standard and very natural.

The given word order is very natural, but Catalan does allow some flexibility.

Standard version:

• Si l'adreça és correcta, Correus lliurarà el paquet demà.

You might also hear or see:

• Si l'adreça és correcta, demà Correus lliurarà el paquet.
• Correus lliurarà el paquet demà si l'adreça és correcta.

All of these are possible, though they may shift emphasis slightly.

The original sentence is a neutral, standard way to say it.

Because paquet is a masculine singular noun, so it takes the article el:

• el paquet = the package / the parcel

Compare:

• el llibre = the book
• la carta = the letter

So:

• Correus lliurarà el paquet demà. = The postal service will deliver the package tomorrow.

Yes. Demà means tomorrow, and Catalan allows some flexibility with adverbs of time.

In your sentence:

• Correus lliurarà el paquet demà.

That is perfectly natural. But these are also possible:

• Demà, Correus lliurarà el paquet.
• Correus demà lliurarà el paquet. (less neutral in many contexts, but possible)
• Si l'adreça és correcta, demà Correus lliurarà el paquet.

The version with demà at the end is very common and neutral.

Even though correus literally looks like the plural of correu (mail/post), here Correus is the name of an institution, so it is treated as a singular entity.

That is why the verb is singular:

• Correus lliurarà = singular
• not Correus lliuraran

This is similar to how some company or organization names may look plural in English but take a singular verb depending on usage.

So in this sentence, think of Correus as a single organization: the postal service.