O contador vai calcular o faturamento.

Because vai agrees with o contador, which is third person singular.

The verb ir in the present tense changes like this:

• eu vou
• você/ele/ela vai
• nós vamos
• vocês/eles/elas vão

Since o contador = he / the accountant, the correct form is vai.

So:

• Eu vou calcular... = I am going to calculate...
• O contador vai calcular... = The accountant is going to calculate...
• Os contadores vão calcular... = The accountants are going to calculate...

Here, contador means accountant.

This can be confusing because it looks a bit like the English word counter, but in business or office contexts, contador usually means a professional who works with accounting, taxes, financial records, and similar tasks.

So in this sentence, it is not a machine or device that counts things. It is a person: the accountant.

O is the masculine singular definite article, meaning the.

So:

• o contador = the accountant
• um contador = an accountant / one accountant

Portuguese uses articles very naturally before nouns, often more often than English does. In this sentence, o contador refers to a specific accountant, not just any accountant.

Vai calcular is the very common ir + infinitive future construction in Brazilian Portuguese.

It works like English is going to calculate:

• vai = goes / is going
• calcular = to calculate

Together, vai calcular means something like is going to calculate.

Brazilian Portuguese uses this structure all the time in everyday speech. A more formal or literary alternative would be:

• O contador calculará o faturamento.

That is correct, but it sounds more formal and less conversational.

Not really. In this sentence, vai is part of a future expression, not a physical movement.

So vai calcular does not mean that the accountant is physically going somewhere in order to calculate. It simply marks a future action.

This is very similar to English is going to calculate, where going often does not imply actual movement either.

Faturamento is a business/accounting term. It usually refers to revenue, billing, or turnover, depending on context.

A very important point: faturamento is not the same as profit.

For example:

• faturamento = money brought in through sales or billing
• lucro = profit
• receita = revenue/income, often a broader term depending on context

So if a learner sees faturamento, it is better to think of sales revenue or amount billed, not earnings after costs.

Because o faturamento is another noun phrase, and it also takes its own article.

Portuguese does not use one article for both nouns here. Each noun phrase is built separately:

• o contador
• o faturamento

In this sentence, o faturamento suggests a specific revenue figure, billing total, or sales total that is being calculated.

Grammatically, people might understand it, but in normal Portuguese it sounds unnatural or very telegraphic.

In Brazilian Portuguese, articles are usually kept in sentences like this:

• O contador vai calcular o faturamento.

Without the articles, it can sound like:

• a headline
• a note
• very abbreviated speech

So for standard, natural Portuguese, keep o before both nouns here.

A simple approximate pronunciation is:

O contador vai calcular o faturamento
u con-ta-DOR vai cal-cu-LAR u fa-tu-ra-MEN-tu

A few pronunciation notes for Brazilian Portuguese:

• o at the end of a word often sounds like u
• contador is stressed on the last syllable: -dor
• calcular is stressed on the last syllable: -lar
• faturamento is stressed on men

A rough English-style approximation could be:

oo con-tah-DOR vai cal-coo-LAR oo fah-too-rah-MEN-too

It will vary by region, but that is a useful starting point.

You would change the article and noun to match gender and number.

Examples:

• A contadora vai calcular o faturamento.
  = The female accountant is going to calculate the revenue.

• Os contadores vão calcular o faturamento.
  = The accountants are going to calculate the revenue.

• As contadoras vão calcular o faturamento.
  = The female accountants are going to calculate the revenue.

Notice that the verb also changes in the plural:

• singular: vai
• plural: vão

Yes. That sentence is correct.

The difference is mainly style:

• O contador vai calcular o faturamento. = more common in everyday Brazilian Portuguese
• O contador calculará o faturamento. = more formal, more written, sometimes more official in tone

Both express future meaning, but vai calcular is the form learners will hear much more often in conversation.