Proteja o cérebro com o capacete.

Proteja is the imperative form used to give a command or instruction, in the você form.

It comes from the verb proteger (to protect).

So:

• proteja = protect! / please protect
• it sounds like a formal or neutral instruction, very common in signs, warnings, and public messages

Grammatically, this form is the same as the present subjunctive for você/ele/ela:

• que você proteja
• proteja você

In Brazilian Portuguese, this is the normal way to make a command addressed to você.

Because the sentence is using the você command form.

With proteger, the command forms are different depending on who you are talking to:

• tu: protege
• você: proteja

In most of Brazil, você is extremely common, so proteja is a very natural choice for a general instruction.

Also, the spelling changes from g to j before a so the sound stays the same:

• proteger → proteja

If it stayed protega, the pronunciation would change, so Portuguese uses j to keep the zh sound.

Portuguese often uses the definite article with body parts when the owner is already obvious.

So instead of saying:

• Proteja seu cérebro

it is very natural to say:

• Proteja o cérebro

The idea is that the brain being referred to is obviously your brain, so Portuguese does not always need the possessive.

This is very common with body parts:

• Lave as mãos = Wash your hands
• Feche os olhos = Close your eyes
• Levante a cabeça = Raise your head

Using seu cérebro is possible, but it can sound a little more emphatic or less idiomatic in a basic instruction like this.

Because both cérebro and capacete are masculine singular nouns.

So they take the masculine singular definite article o:

• o cérebro
• o capacete

This is just normal noun gender agreement in Portuguese.

Here, com means with or using.

So com o capacete means:

• with the helmet
• by using the helmet

It shows the means or tool used to do the protecting.

So the structure is basically:

• Protect the brain
  • with the helmet

In standard Portuguese, com + o stays:

• com o

Unlike some other very common contractions:

• de + o = do
• em + o = no
• a + o = ao

So:

• com o capacete is correct
• there is no standard written contraction here

In fast speech, people may reduce sounds a little, but in normal writing it remains com o.

It is best understood as neutral to formal, the kind of language you might see in:

• a safety notice
• a public campaign
• an instruction manual
• a warning sign

That is because proteja is the você command form, which is very common in public-facing Brazilian Portuguese.

It is not especially stiff or overly formal; it just sounds like standard instruction language.

Yes. The sentence structure is perfectly normal:

• Proteja = verb
• o cérebro = direct object
• com o capacete = prepositional phrase showing the means

So the order is:

• Verb + object + with-phrase

This is a very common and natural pattern in Portuguese.

In real context, people will normally understand it as describing how to protect the brain: by using the helmet.

So the intended meaning is:

• Protect the brain by wearing/using the helmet

Still, if you want to be extra explicit, Portuguese could also say:

• Use o capacete para proteger o cérebro
• Proteja a cabeça com o capacete

Those versions can feel a little clearer in some situations.

Cérebro is grammatically correct and fully understandable, but in many everyday safety messages, cabeça may sound more natural.

For example:

• Proteja a cabeça com o capacete

This can sound more direct because a helmet physically covers the head, not the brain itself.

That said, using cérebro gives the sentence a stronger safety emphasis, because it highlights what you are ultimately protecting.

So:

• cabeça = more everyday / physical
• cérebro = more specific / more medically or emotionally impactful

No. Portuguese often leaves out the subject pronoun when it is clear from the verb form.

So:

• Proteja o cérebro com o capacete.

already clearly works as a command addressed to você.

You could say:

• Você, proteja o cérebro com o capacete.

but that would usually sound more emphatic than necessary.

A simple approximation is:

• pro-TE-zha u SEH-re-bro com u ka-pa-SE-chi

A few useful details:

• proteja: the j sounds like the s in measure
• cérebro: stress on the first syllable
• capacete: stress on ce

A more technical pronunciation guide would be roughly:

• [pɾoˈte.ʒɐ u ˈsɛ.ɾe.bɾu kõ u kapaˈsɛtʃi]

The exact sound will vary a bit by region, but that is a good Brazilian standard model.