O perito mostrou a licença.

Because o is the masculine singular definite article, meaning the.

In Portuguese, articles are used more often than in English. So o perito means the expert / the specialist. Leaving out the article is sometimes possible, but it would usually sound less natural in a simple sentence like this unless you were using perito in a more general or predicate sense.

• o = the for a masculine singular noun
• perito = a masculine singular noun

So the noun and article agree in gender and number.

Perito usually means expert, specialist, or in some contexts expert witness / forensic expert.

The exact meaning depends on context:

• in everyday language: an expert
• in legal or police contexts: a specialist appointed to examine something
• in insurance or technical contexts: an assessor / examiner

So it is a more formal word than just especialista in some situations.

Mostrou is the 3rd person singular of the preterite (also called the simple past) of mostrar.

So:

• mostrar = to show
• ele/ela/você mostrou = he/she/you showed

This tense is used for a completed action in the past. The sentence presents the showing as a finished event.

A few forms of mostrar in the preterite:

• eu mostrei = I showed
• tu mostraste = you showed
• ele/ela/você mostrou = he/she/you showed
• nós mostrámos = we showed (European Portuguese spelling and pronunciation distinction)
• eles/elas/vocês mostraram = they/you showed

In this sentence, the subject is explicitly stated: O perito.

Portuguese often allows subject pronouns like ele or ela to be omitted, but here the full noun phrase is present, so there is no ambiguity:

• O perito mostrou a licença. = The expert showed the licence.

If the sentence were just Mostrou a licença, then context would be needed to know who did it.

Here, a means the, not a/an.

That is because licença is a feminine singular noun, so its definite article is a:

• a licença = the licence

This can be confusing because English a looks identical. In Portuguese:

• a = the (feminine singular definite article)
• uma = a/an (feminine singular indefinite article)

So:

• a licença = the licence
• uma licença = a licence

Yes. Licença can mean several related things depending on context, including:

• licence / permit
• permission
• in expressions, even excuse me

For example:

• Carta de condução com licença would relate to permission or licensing
• Com licença = Excuse me / May I?

So even if your sentence’s meaning is already clear, it is useful to know that licença is a broader word than English licence in some contexts.

Because a licença is the direct object, and normal Portuguese word order is:

Subject + Verb + Object

So:

• O perito = subject
• mostrou = verb
• a licença = direct object

This is the same basic order as English:

• The expert showed the licence.

Portuguese can change word order for emphasis, but this sentence uses the most neutral and common pattern.

In European Portuguese, licença is pronounced approximately like:

lee-SEN-suh

A few important points:

• the stress is on -cen-
• the ç makes an s sound
• the final a in European Portuguese is usually reduced, so it is not a strong English-style ah

A rougher European Portuguese approximation would be:

• lee-SEN-suh or lee-SEN-sɐ

The cedilla in ç is there to show that the c is pronounced like s, not k.

In European Portuguese, mostrou is approximately:

mush-TROH or mosh-TROH, depending on the speaker

Useful pronunciation notes:

• the stress is on the last syllable: -trou
• the ou is usually pronounced like a closed o sound in European Portuguese
• the s before t often sounds like sh in European Portuguese

So many learners hear something close to:

• mosh-TROH

That is a normal European Portuguese feature.

The accent mark in licença helps show the stress pattern and pronunciation.

• licença is stressed on -cen-
• the written accent ã also shows a nasal sound

So licença is not pronounced like it would be if you simply followed the most basic spelling rules without the accent.

By contrast, mostrou does not need an accent mark because its stress follows the normal spelling rules of Portuguese.

So the accent is not decorative: it gives pronunciation information.

Yes. Once a licença is already known from context, Portuguese can replace it with a direct object pronoun:

• O perito mostrou-a. = The expert showed it.

Because licença is feminine singular, the pronoun is a.

In European Portuguese, when the pronoun comes after the verb, it is attached with a hyphen:

• mostrou-a

This is very common in written Portuguese, though in speech people may often prefer the full noun or structure the sentence differently depending on context.

The sentence itself works in both European and Brazilian Portuguese:

• O perito mostrou a licença.

The main differences would be in pronunciation and some usage preferences, not in the basic grammar.

For example:

• European Portuguese often reduces unstressed vowels more strongly
• the pronoun system and pronoun placement can differ more noticeably in other sentences
• some contexts might prefer different vocabulary choices depending on the country

But this exact sentence is perfectly normal in both varieties.