Preciso imprimir este arquivo antes que a reunião comece, porque a impressora do escritório é lenta.

In Brazilian Portuguese, the subject pronoun is often omitted when the verb form already makes the subject clear.

• Preciso = I need
• Eu preciso also means I need

Because preciso is the 1st person singular form, Brazilians usually understand that the subject is eu even when it is not stated. Including eu is possible, but it can sound more emphatic or contrastive depending on context.

After verbs like precisar, Portuguese commonly uses another verb in the infinitive.

• Preciso imprimir = I need to print
• literally: I need print

This works much like English need to + verb, except Portuguese does not use a separate word equivalent to to here.

Other examples:

• Preciso sair = I need to leave
• Quero estudar = I want to study

Both can mean this file, but the textbook distinction is:

• este = this, near the speaker
• esse = that, near the listener
• aquele = that over there, farther from both

In everyday Brazilian Portuguese, many speakers use esse much more often than este, even where a grammar book might expect este. So este arquivo is correct and a bit more formal or careful, while esse arquivo would also be very common in speech.

Because antes que triggers the subjunctive.

So:

• antes que ... comece = correct
• antes que ... começa = not correct here

The verb comece is the present subjunctive of começar. Portuguese uses the subjunctive after certain conjunctions when talking about something that has not happened yet, is uncertain, expected, desired, or dependent on another action.

Here, the meeting has not started yet, so Portuguese says:

• antes que a reunião comece = before the meeting starts

Yes. Both are possible, but they are built differently.

1. antes que a reunião comece

   • uses a full clause with a conjugated verb in the subjunctive

2. antes de a reunião começar

   • uses de
     • subject + infinitive

Both mean essentially the same thing here: before the meeting starts.

In everyday Brazilian Portuguese, you may also hear:

• antes da reunião começar

That is very common in speech, although more traditional grammar often prefers antes de a reunião começar.

Comece is the present subjunctive form of começar for ele/ela/você.

Conjugation:

• eu comece
• você/ele/ela comece
• nós comecemos
• vocês/eles/elas comecem

In this sentence, a reunião is singular, so Portuguese uses the ela form:

• a reunião comece

Do not confuse it with the present indicative:

• a reunião começa = the meeting starts / is starting

After antes que, you need the subjunctive form comece.

Do is a contraction of:

• de + o = do

So:

• a impressora do escritório literally means the printer of the office
• natural English: the office printer or the printer in the office

This kind of contraction is extremely common in Portuguese:

• de + a = da
• em + o = no
• em + a = na

Examples:

• o livro do professor = the teacher’s book
• a porta da sala = the room’s door / the door of the room

Portuguese uses articles differently depending on the structure.

• a reunião = the meeting
• a impressora = the printer

But when a demonstrative like este comes before a noun, it already does the job of specifying it, so you normally do not also add the article in this kind of standard structure:

• este arquivo = this file

So the sentence naturally has:

• este arquivo
• a reunião
• a impressora

In Brazilian Portuguese, articles are very frequent, but demonstratives like este, esse, aquele usually replace the article rather than combine with it in this position.

Because adjectives usually agree with the noun they describe in gender and number.

• impressora is feminine singular
• so the adjective must also be feminine singular: lenta

Compare:

• o computador é lento = the computer is slow
• a impressora é lenta = the printer is slow
• as impressoras são lentas = the printers are slow

Both ser and estar can sometimes translate as to be, but they are used differently.

Here, é lenta describes the printer as having the characteristic of being slow, or at least being generally slow in that context.

• é lenta = is slow
• está lenta = is being slow / is currently slow

In this sentence, é lenta sounds more natural because it explains the reason in a general way:

• I need to print it before the meeting starts because the office printer is slow.

If you wanted to stress a temporary problem, está lenta could make sense in another context.

The comma separates the main statement from the reason that follows.

Main part:

• Preciso imprimir este arquivo antes que a reunião comece

Reason:

• porque a impressora do escritório é lenta

This comma is very natural in Portuguese, especially in longer sentences. Even when punctuation can vary by style, using the comma here helps readability.

Reunião is pronounced roughly like heh-oo-nee-OWng, though the final sound is nasal and does not match English exactly.

A few points:

• ão is a very common Portuguese ending
• it is nasal
• the ã is not the same as a plain a
• the final o is part of the nasal diphthong, not a strong separate English-style o

This ending appears in many nouns:

• reunião = meeting
• impressão = printing / impression
• situação = situation

It is a good idea to listen to native audio for ão, because it is one of the sounds English speakers often need time to get used to.

Yes, porque is correct here because it means because and introduces the reason.

• porque = because
• por que = why / for what reason
• porquê = the reason (a noun)
• por quê = why, usually at the end of a question

In this sentence:

• porque a impressora do escritório é lenta = because the office printer is slow

So the one-word form porque is exactly what you want.