A não ser que o quiosque esteja fechado, nós vamos jantar ali depois da feira.

A não ser que means unless.

So:

A não ser que o quiosque esteja fechado...
= Unless the kiosk is closed...

It is a normal and useful expression in Portuguese. You will hear it in both speech and writing. A close alternative is a menos que, which also means unless.

Examples:

• A não ser que chova, vamos sair. = Unless it rains, we’re going out.
• A menos que ele ligue, eu vou embora. = Unless he calls, I’m leaving.

Because a não ser que triggers the subjunctive.

After expressions like a não ser que, Portuguese usually uses the present subjunctive because the situation is uncertain, hypothetical, or conditional.

• está = indicative
• esteja = present subjunctive

So:

• o quiosque está fechado = the kiosk is closed
• a não ser que o quiosque esteja fechado = unless the kiosk is closed

This is one of the most important patterns to learn:

• a não ser que + subjunctive
• a menos que + subjunctive

Esteja is the present subjunctive form of estar.

Here is the full present subjunctive of estar:

• eu esteja
• você / ele / ela esteja
• nós estejamos
• vocês / eles / elas estejam

In the sentence, the subject is o quiosque, which is third person singular, so the form is esteja.

Portuguese often uses definite articles more than English does.

So o quiosque literally means the kiosk. In context, it may refer to a specific kiosk that both speakers already know about.

English sometimes omits the article where Portuguese keeps it, but here the kiosk sounds natural in English too.

Also:

• o = masculine singular definite article
• quiosque is masculine, so it takes o

Quiosque usually means a kiosk, small stand, or small snack/drink stand. In Brazil, it often refers to a casual place selling food or drinks, especially in public areas, parks, beaches, or near markets.

So in this sentence, it sounds like they plan to eat at a small stand or casual food spot.

Pronunciation in Brazilian Portuguese is approximately: kee-O-skee

In Brazilian Portuguese, ir + infinitive is very common for talking about the future.

So:

• nós vamos jantar = we are going to have dinner / we’ll have dinner
• jantaremos = we will have dinner

Both are correct, but vamos jantar is more natural and common in everyday speech in Brazil.

This is similar to English using we’re going to eat instead of we shall eat.

No, nós is not strictly necessary.

Portuguese often drops subject pronouns when the verb already makes the subject clear.

So these both work:

• Nós vamos jantar ali depois da feira.
• Vamos jantar ali depois da feira.

Including nós can add clarity, emphasis, or contrast.

For example:

• Nós vamos jantar ali, mas eles vão para casa. = We’re going to have dinner there, but they’re going home.

Ali means there, usually referring to a place that is not right here, but is relatively specific or identifiable.

A rough comparison:

• aqui = here
• ali = there, over there
• lá = there, often farther away or less specific

In real Brazilian Portuguese, ali and lá can overlap a lot, but ali often suggests a place the speaker can point to or has in mind more precisely.

So vamos jantar ali suggests something like: we’re going to eat there / over there

Depois da feira means after the fair/market.

Breakdown:

• depois de = after
• de + a = da

So:

• depois de a feira becomes depois da feira

In Brazil, feira often refers to a street market or open-air market, not only a fair in the amusement or festival sense.

So depending on context, depois da feira may mean:

• after the market
• after the street fair
• after the fair

Because feira is being used with the definite article a.

• de + a = da

So:

• depois da feira = after the fair / after the market

This contraction is extremely common in Portuguese:

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

Examples:

• o carro do João = João’s car
• a porta da casa = the door of the house

Yes. Portuguese allows some flexibility.

Original:

• A não ser que o quiosque esteja fechado, nós vamos jantar ali depois da feira.

You could also say:

• Nós vamos jantar ali depois da feira, a não ser que o quiosque esteja fechado.

The meaning stays basically the same: We’re going to have dinner there after the fair, unless the kiosk is closed.

Putting the unless clause first makes the condition sound a bit more prominent.

Yes. Jantar can be:

• a verb: to have dinner / to dine
• a noun: dinner

In this sentence, it is a verb because it follows vamos:

• vamos jantar = we are going to have dinner

As a noun:

• O jantar está pronto. = Dinner is ready.

This is common in Portuguese with some meal words:

• almoçar = to have lunch
• jantar = to have dinner

Yes, that is possible, but it is a slightly different structure.

• A não ser que o quiosque esteja fechado = unless the kiosk is closed
• Se o quiosque não estiver fechado = if the kiosk isn’t closed

These are very close in meaning in many contexts, but a não ser que directly corresponds to unless, while se... não... corresponds more literally to if... not...

Also notice that se in this kind of future-oriented condition also uses the subjunctive:

• se o quiosque não estiver fechado

Yes, it is natural and correct.

It sounds like a normal everyday sentence. A Brazilian speaker might also say slightly more conversational versions, such as:

• A não ser que o quiosque esteja fechado, vamos jantar ali depois da feira.
• Se o quiosque não estiver fechado, a gente janta ali depois da feira.
• A menos que o quiosque esteja fechado, a gente vai jantar ali depois da feira.

In casual Brazilian speech, a gente is often used instead of nós, but the original sentence is perfectly good Portuguese.