O relatório foi revisto antes da reunião.

It is the passive voice.

• foi = the pretérito perfeito simples of ser for ele/ela/você
• revisto = the past participle

So foi revisto means was reviewed.

This structure works like English was + past participle:

• O relatório foi revisto. = The report was reviewed.

The passive is used when the focus is on the thing affected by the action, not on the person who did it.

Portuguese uses the passive for the same reasons English does:

• the person who did the action is unknown
• the person is not important
• the speaker wants to focus on the result or on the object

So O relatório foi revisto antes da reunião focuses on the report, not on the reviewer.

An active version would be:

• A equipa reviu o relatório antes da reunião. = The team reviewed the report before the meeting.

Because this sentence uses the verb rever, whose past participle is revisto.

• rever → revisto
• ver → visto

So:

• O relatório foi revisto = The report was reviewed

Revisado would come from revisar, which is a different verb. In some contexts rever and revisar can both relate to reviewing or revising, but they are not the same verb grammatically.

Because the past participle agrees with o relatório, which is masculine singular.

In passive constructions with ser, the participle changes to match the noun:

• O relatório foi revisto — masculine singular
• A ata foi revista — feminine singular
• Os relatórios foram revistos — masculine plural
• As atas foram revistas — feminine plural

So the -o is not random; it shows agreement.

O is the definite article, meaning the.

So:

• o relatório = the report

Portuguese uses definite articles very regularly. Here it shows that we are talking about a specific report, not just any report.

Compare:

• O relatório foi revisto = The report was reviewed
• Um relatório foi revisto = A report was reviewed

Because de + a contracts to da in normal Portuguese.

The expression is antes de = before.
When the next noun has the article a, you usually contract them:

• antes de + a reunião → antes da reunião

This kind of contraction is very common:

• de + o → do
• de + a → da
• de + os → dos
• de + as → das

So antes da reunião is the natural standard form.

When antes is followed by a noun or infinitive phrase, yes, it normally uses de.

Examples:

• antes da reunião = before the meeting
• antes do almoço = before lunch
• antes de sair = before leaving

So in this sentence, antes da reunião is built from antes de + a reunião.

Yes. Portuguese allows some flexibility.

The original sentence is neutral and very natural:

• O relatório foi revisto antes da reunião.

You can also say:

• Antes da reunião, o relatório foi revisto.

That version puts more emphasis on the time phrase before the meeting.

Both are correct. The first is probably the most neutral everyday order.

You can add the agent with por, which often contracts with the article:

• por + o → pelo
• por + a → pela
• por + os → pelos
• por + as → pelas

Examples:

• O relatório foi revisto pelo diretor antes da reunião.
• O relatório foi revisto pela equipa antes da reunião.

So pelo diretor means by the director.

The tense of foi is pretérito perfeito simples.

In this sentence, it presents the reviewing as a completed past action:

• the report was reviewed
• that happened before the meeting

So foi revisto is a completed passive event in the past.

If you wanted a different time relationship, you might use a different structure:

• O relatório estava revisto = the report was in a reviewed state
• O relatório tinha sido revisto = the report had been reviewed

The accent marks help show stress and sometimes vowel quality.

• relatório is stressed on tó
• reunião is stressed on the final ão

Without the accents, the pronunciation rules would point you differently, so the written accents are important.

They are part of the correct spelling, not optional marks.

A rough European Portuguese pronunciation is:

u rɨlɐ-TÓ-ryu foi rɨ-VIʃ-tu AN-t(ɨ)zh dɐ ryu-ny-AW̃

A few useful pronunciation notes:

• O often sounds close to u in European Portuguese
• unstressed vowels are reduced a lot
• s in antes sounds like zh before d in connected speech
• ão is a nasal ending, which English does not really have

So the sentence may sound more compressed than a learner expects. European Portuguese often reduces unstressed syllables quite strongly.