O microempreendedor individual precisa de um CNPJ.

It is a specific legal/business category in Brazil, often abbreviated as MEI.

A literal breakdown is:

• micro = micro, very small
• empreendedor = entrepreneur
• individual = individual, sole

But in real use, microempreendedor individual is best understood as one fixed term: a sole micro-entrepreneur / self-employed person registered under the MEI system.

So this is not just any entrepreneur who happens to be individual; it is the name of a formal category.

O is the masculine singular definite article, so literally it is the.

However, Portuguese often uses the definite article to talk about a whole class or category in a general way. So:

• O microempreendedor individual precisa de um CNPJ.

can mean something like:

• A microentrepreneur needs a CNPJ
• An individual micro-entrepreneur needs a CNPJ
• The individual micro-entrepreneur needs a CNPJ

In English, we often leave the article out or choose a/an in these general statements. Portuguese commonly uses o/a/os/as for this kind of generic meaning.

In Portuguese, adjectives often come after the noun.

So:

• empreendedor individual = individual entrepreneur / sole entrepreneur

That word order is normal in Portuguese. Also, microempreendedor individual is a fixed official expression, so the order is not really flexible here.

For an English speaker, it may feel reversed, but in Portuguese this is standard.

Yes. In Brazilian Portuguese, microempreendedor individual is a set expression, and it is very commonly shortened to MEI.

So these are closely connected:

• microempreendedor individual
• MEI

In everyday Brazilian usage, people often say things like:

• Ele é MEI.
• Ela abriu um MEI.

So if you see MEI, it is referring to this same category.

Because the verb precisar normally takes the preposition de when it is followed by a noun.

Here, the thing needed is a noun phrase:

• um CNPJ

So you get:

• precisa de um CNPJ

Other examples:

• Eu preciso de ajuda.
• Ela precisa de dinheiro.
• Nós precisamos de tempo.

A useful rule for learners is:

• precisar de + noun
• often precisar + infinitive when followed by another verb in Brazilian Portuguese

For example:

• Ele precisa trabalhar. = He needs to work.

But in your sentence, since CNPJ is a noun, de is the normal choice.

Because do is a contraction of:

• de + o = do

But here the sentence has:

• de + um

and in standard modern Portuguese, that usually stays separate:

• de um

So:

• precisa do CNPJ = needs the CNPJ
• precisa de um CNPJ = needs a CNPJ

That is an important difference.

You may occasionally see forms like dum in literary or more old-fashioned/colloquial language, but for normal modern Brazilian Portuguese, de um is the safe standard form.

CNPJ is a Brazilian business registration/tax identification number.

It stands for:

• Cadastro Nacional da Pessoa Jurídica

It is treated as a masculine noun, so you say:

• um CNPJ
• o CNPJ

That masculine gender is usually understood from the head word cadastro, which is masculine.

So even though it is an acronym, it still behaves like a normal masculine noun in the sentence.

In Brazilian Portuguese, it is normally pronounced letter by letter:

• cê-ene-pê-jota

So the full sentence would include that pronunciation at the end.

If you are reading it aloud, you would not try to pronounce CNPJ as one single word.

A rough Brazilian Portuguese pronunciation guide is:

• microempreendedor ≈ mee-kroh-em-preh-en-deh-DOR
• individual ≈ een-dee-vee-doo-AL

The stressed syllables are:

• microempreendeDOR
• individuAL

And the whole sentence, very roughly, is:

• O microempreendedor individual precisa de um CNPJ.
• ≈ oo mee-kroh-em-preh-en-deh-DOR een-dee-vee-doo-AL preh-SEE-zuh djee oong cê-ene-pê-JO-tah

This is only an approximation for English speakers, but it helps with the main stress.

The plural version would be:

• Os microempreendedores individuais precisam de um CNPJ.

Changes:

• O → Os
• microempreendedor → microempreendedores
• individual → individuais
• precisa → precisam

Notice that um CNPJ can stay singular if the meaning is each one needs a CNPJ.

You may also hear:

• Os microempreendedores individuais precisam de CNPJ.

That sounds a bit more general, like need CNPJ registration / need a CNPJ in general.

Because in this sentence it is being used as a common noun expression, not as a title.

So lowercase is normal:

• o microempreendedor individual

But the acronym is capitalized:

• CNPJ
• MEI

In official documents, headings, or branding, you may sometimes see more capitalization than usual, but in normal sentence writing, lowercase is standard for microempreendedor individual.