Quando o portão abriu, as passageiras pararam de falar e começaram a embarcar.

Quando by itself is the normal word for when.

In this sentence, it introduces a time clause:

• Quando o portão abriu = When the gate opened

You could hear longer patterns in speech, but here quando alone is the standard and natural choice.

The comma separates the opening time clause from the main action:

• Quando o portão abriu, = the time/background event
• as passageiras pararam... e começaram... = the main actions

This is very similar to English:

• When the gate opened, the passengers stopped talking...

The comma is especially common when the quando clause comes first.

Not exactly. Portão usually means gate or large door/gate, often something bigger than a normal porta.

A helpful comparison:

• porta = door
• portão = gate / large door

The ending -ão here often gives the idea of something larger.

Portuguese uses definite articles much more often than English.

So where English might say:

• When the gate opened

Portuguese naturally says:

• Quando o portão abriu

The article o means the and sounds completely normal here.

Abriu is the preterite (simple past) of abrir = to open.

• abrir = to open
• abriu = opened

It is used because the opening is seen as a completed event in the past. The gate opened, and then the next actions happened.

In Portuguese, verbs like abrir can be used in a very natural intransitive way:

• O portão abriu = The gate opened

This does not necessarily focus on who opened it. It just states that it opened.

If you wanted to emphasize that someone opened it, you could say something like:

• Abriram o portão = They opened the gate
• O portão foi aberto = The gate was opened

But in your sentence, o portão abriu is simple and natural.

Yes, passageiras is the feminine plural form of passenger.

• passageiro = male passenger / passenger (masculine singular)
• passageira = female passenger
• passageiros = male passengers / mixed group
• passageiras = female passengers

So as passageiras suggests the group being referred to is female.

As is the feminine plural form of the.

• a passageira = the female passenger
• as passageiras = the female passengers

Portuguese usually includes the article where English also would, and often even where English might omit it.

This is a very common pattern:

• parar de + infinitive = to stop doing something

So:

• pararam = they stopped
• de falar = speaking / talking

Together:

• pararam de falar = they stopped talking

This is one of the most useful verb patterns to memorize.

Examples:

• parei de fumar = I stopped smoking
• ela parou de rir = she stopped laughing

Because different verbs require different patterns in Portuguese.

Two important ones are:

• parar de + infinitive = to stop doing
• começar a + infinitive = to start doing

So:

• pararam de falar = stopped talking
• começaram a embarcar = started boarding

Unfortunately, this is something you mostly learn verb by verb.

Both are in the preterite too, just like abriu.

• pararam = they stopped
• começaram = they started

The preterite is used because these are completed past actions in a sequence:

1. the gate opened
2. the passengers stopped talking
3. they started boarding

This makes the sentence feel like a clear past event.

Because after parar de and começar a, Portuguese uses the infinitive.

So the structure is:

• parar de + infinitive
• começar a + infinitive

That gives:

• pararam de falar
• começaram a embarcar

English often uses an -ing form in translation (stopped talking, started boarding), but Portuguese uses the infinitive here.

Embarcar means to board or to embark.

It can be used for different kinds of transport, depending on context:

• plane
• train
• bus
• ship

In many travel contexts, embarcar is the standard verb for boarding.

So here it simply means they began getting on the transport they were supposed to take.

Portuguese often leaves that unstated when the context makes it obvious.

So:

• começaram a embarcar = they began boarding

It works like English They started boarding. You do not always need to say the plane, the bus, etc., if everyone already knows what is being boarded.

Portuguese often omits subject pronouns when the verb ending already makes the subject clear.

Here:

• pararam
• começaram

Both clearly indicate they.

And the noun as passageiras is already present, so adding elas would be unnecessary.

A little, but the original order is very natural.

The sentence is:

• Quando o portão abriu, as passageiras pararam de falar e começaram a embarcar.

This flows naturally as:

1. time/background
2. who did the action
3. what happened

You could rearrange things in some contexts, but the original version is the most straightforward and idiomatic.

Two useful pronunciation points:

• portão has the nasal ending -ão, which is very common in Brazilian Portuguese.
• começaram has ç, which sounds like s.

Roughly:

• portão ≈ por-TAWN with a nasal ending
• começaram ≈ ko-me-SA-rãw with the last syllable unstressed compared to the ça

A few details:

• ão is not an English sound exactly; it is nasal.
• ç always gives an s sound before a, o, u.

The accents help show pronunciation.

• começaram: the ç is not a stress mark; it shows the s sound.
• portão: the ã shows nasal pronunciation.

So these marks are not decorative; they give important sound information.

Not naturally in this exact version.

The preterite works well because the sentence tells a sequence of completed events:

• the gate opened
• they stopped talking
• they started boarding

If you used the imperfect, it would give a different feel, more like ongoing background or habitual action. Here the preterite is the natural tense for a one-time event sequence.

In this sentence, to talk is the most natural translation:

• pararam de falar = stopped talking

Falar can mean to speak or to talk, depending on context. Here it refers to the passengers chatting, so talking fits best.