O site do banco está fora do ar hoje.

In Portuguese, nouns often appear with a definite article when you are talking about a specific thing. Here, o site means the website.

So:

• o site = the website
• site by itself can sound less natural here unless the context is very different

Portuguese uses articles more often than English does, especially with specific, known things.

Site is a borrowed word in Portuguese, and in Brazilian Portuguese it is treated as masculine, so it takes o:

• o site
• um site

There is not always a logical reason learners can see right away; sometimes borrowed nouns simply settle into one gender by usage. You should just memorize o site as a chunk.

Do is a contraction of:

• de + o = do

So:

• do banco literally = of the bank
• in natural English here = the bank’s

That means:

• o site do banco = the bank’s website

This de + article structure is very common in Portuguese:

• o carro do meu amigo = my friend’s car
• a agência do banco = the bank branch

Yes. Banco can mean different things depending on context, including:

• bank (financial institution)
• bench
• sometimes seat/stool

In this sentence, because of site and the general context, banco clearly means bank.

Portuguese has two main verbs for to be: ser and estar.

Here we use estar because fora do ar describes a temporary condition or state:

• está fora do ar = is down / is offline / is unavailable

If you used é, it would sound wrong here, because the website is not permanently defined by being down. It is just in that condition at the moment.

Literally, fora do ar means out of the air.

But as an expression, it means things like:

• offline
• down
• not working
• off the air

It can be used for:

• websites
• radio or TV broadcasts
• systems or services

Examples:

• O sistema está fora do ar. = The system is down.
• A rádio está fora do ar. = The radio station is off the air.

Usually no. A word-for-word translation sounds odd in English. It is better to translate the whole expression naturally based on context.

For a website, the best translations are often:

• is down
• is offline
• is unavailable

So although fora do ar literally means out of the air, you should learn it as a fixed expression.

Hoje means today, and adverbs of time are quite flexible in Portuguese. Putting hoje at the end is very natural.

You could also hear:

• Hoje o site do banco está fora do ar.
• O site do banco hoje está fora do ar.

All of these are possible, but the original sentence sounds very normal and neutral.

Yes, if the time is already clear from context.

• O site do banco está fora do ar. = The bank’s website is down.

Adding hoje makes it explicit that this is true today. It can also suggest this may be a temporary issue affecting today in particular.

Yes. In Brazilian Portuguese, site is a very common everyday word for website.

You may also see:

• website in some contexts
• página for page, not usually the whole site

So in normal Brazilian usage:

• o site do banco is completely natural

In Brazil, site is usually pronounced something like sáitchi.

That pronunciation reflects how English loanwords are often adapted to Portuguese sound patterns.

So even though the spelling looks English, the pronunciation in Brazilian Portuguese is usually closer to:

• sáitchi

Yes. In Brazilian Portuguese, cair is often used informally for websites, systems, or internet connections going down.

• O site do banco caiu. = The bank’s website went down.

The difference is:

• está fora do ar describes the current state
• caiu emphasizes the event of going down

Both are common and natural.

It is neutral and very natural. It works well in everyday speech and writing.

• O site do banco está fora do ar hoje. sounds standard and clear.
• A more informal spoken version might be O site do banco tá fora do ar hoje.

Here, tá is a common spoken short form of está in Brazilian Portuguese.

Portuguese does not normally use an apostrophe ’s to show possession the way English does. Instead, it usually uses de plus the possessor:

• o site do banco = the bank’s website
• literally, the website of the bank

This is one of the most common possession patterns in Portuguese, so it is worth getting used to early.

Grammatically, banco could mean bench, but in real usage this sentence strongly points to bank because a bench’s website makes little sense in normal context.

So this is a good example of how context removes ambiguity in Portuguese, just as it does in English.