Eu quero formalizar o negócio.

Yes. In Brazilian Portuguese, subject pronouns are often optional when the verb already makes the subject clear.

• Eu quero formalizar o negócio = I want to formalize the business/deal
• Quero formalizar o negócio means the same thing in most contexts

Including eu can add:

• emphasis
• contrast
• clarity

For example:

• Eu quero formalizar o negócio, mas ele não.
  I want to formalize the deal, but he doesn’t.

Quero is the first-person singular form of the verb querer (to want / to wish).

Conjugation in the present:

• eu quero = I want
• você/ele/ela quer = you/he/she wants
• nós queremos = we want
• vocês/eles/elas querem = you all/they want

So eu quero literally means I want.

Because after querer (to want), Portuguese usually uses another verb in the infinitive.

Structure:

• querer + infinitive

Examples:

• Quero comer = I want to eat
• Quero sair = I want to leave
• Quero formalizar o negócio = I want to formalize the business/deal

This is very similar to English want to + verb.

Formalizar means to make something official, formal, or legally recognized.

Depending on context, it could mean:

• to put something into an official agreement
• to register a business properly
• to make a verbal arrangement official
• to document something formally

So in this sentence, it likely suggests making the business/deal official in some way.

Not always. Negócio is a flexible word in Portuguese. It can mean:

• business
• deal
• transaction
• matter/thing in informal speech

In Eu quero formalizar o negócio, the most likely meanings are:

• the business
• the deal
• the arrangement

The exact meaning depends on context. For example:

• If someone is opening a company, negócio may mean business
• If two people agreed on terms, it may mean deal

O is the masculine singular definite article, meaning the.

• o negócio = the business / the deal

Portuguese uses articles more often than English does. Here, o shows that the speaker is talking about a specific business or deal, not just business in general.

Compare:

• formalizar o negócio = formalize the business/deal
• formalizar um negócio = formalize a business/deal

Yes, negócio is masculine, which is why it takes o.

You can tell from dictionary entries:

• o negócio

Also, many nouns ending in -o are masculine, though that is not a perfect rule.

Examples:

• o negócio
• o carro
• o livro

So:

• o negócio
• um negócio
• esse negócio

Yes. In everyday Brazilian Portuguese, negócio can sometimes mean something like thing, especially when the speaker is being vague.

For example:

• Me passa aquele negócio ali.
  Pass me that thing there.

But in Eu quero formalizar o negócio, that informal meaning is unlikely. Because of formalizar, the sentence strongly suggests business, deal, or arrangement.

Yes, it is natural, especially if the speaker means making a business arrangement official.

Depending on context, Brazilians might also say:

• Quero formalizar isso.
• Quero oficializar o negócio.
• Quero regularizar o negócio.

Each has a slightly different nuance:

• formalizar = make formal / official
• oficializar = make officially recognized
• regularizar = bring into legal or proper compliance

But your original sentence is perfectly normal.

They are similar, but not identical.

• formalizar: to make something formal, often by documentation, agreement, or official procedure
• oficializar: to make something officially recognized

In many contexts they overlap. But formalizar often focuses more on the process of putting something into proper form.

For example:

• formalizar um contrato = formalize a contract
• oficializar uma decisão = make a decision official

In your sentence, formalizar sounds very appropriate if the speaker wants to properly document or register the business/deal.

Yes. That changes the meaning slightly:

• o negócio = the business/deal
• esse negócio = this/that business/deal

Esse points to something more specific, often something already being discussed.

Examples:

• Quero formalizar o negócio = I want to formalize the business/deal
• Quero formalizar esse negócio = I want to formalize this/that deal

In conversation, esse negócio can sound more immediate or situational.

A common Brazilian pronunciation is approximately:

• negócio ≈ neh-GO-see-oh or neh-GOH-syoo, depending on accent

A few helpful points:

• the stress is on gó
• the ó is an open vowel
• in many Brazilian accents, cio can sound somewhat like see-oh or syoo

So the stressed rhythm is:

• ne-GÓ-cio

This is the normal Portuguese word order:

• subject + verb + infinitive + object

So:

• Eu = subject
• quero = main verb
• formalizar = infinitive
• o negócio = object

Portuguese word order is often similar to English here:

• I want to formalize the business
• Eu quero formalizar o negócio

Other orders are possible in special contexts, but this one is the standard and most natural.

Yes, absolutely. In Brazilian Portuguese, formalizar o negócio can mean making a business legal or officially registered.

For example, it might involve:

• getting a CNPJ
• registering the company
• creating legal documentation
• becoming compliant with regulations

So depending on context, the sentence could mean:

• I want to make the business official
• I want to register the business properly
• I want to formalize the deal

Sometimes, yes, but the meaning changes.

• negócio = business, deal, venture, arrangement
• empresa = company, firm, enterprise

So:

• Quero formalizar o negócio may refer to the activity, venture, or deal
• Quero formalizar a empresa sounds more specifically like making the company itself official/legal

If you mean an actual company as a legal entity, empresa may be more precise. If you mean the overall business idea or arrangement, negócio may fit better.