O reconhecimento de firma é feito no cartório.

O is the definite article the for a masculine singular noun.

Here, the main noun is reconhecimento, which is masculine:

• o reconhecimento
• not a reconhecimento

So O reconhecimento de firma means the signature notarization / the notarization of a signature.

This is a fixed expression in Brazilian Portuguese. It refers to a notarial procedure in which a signature is officially verified at a cartório.

A few important notes:

• firma here does not mean company
• in this expression, firma refers to the signature specimen registered at the notary office
• so the whole expression is best learned as one unit: reconhecimento de firma

Even if the learner already knows the overall meaning, it helps to know that this is a very common bureaucratic/legal phrase in Brazil.

In everyday Portuguese, assinatura is the normal word for signature.

But in the legal/notarial expression reconhecimento de firma, Portuguese uses firma, not assinatura. This is traditional legal/bureaucratic wording.

So:

• everyday word: assinatura
• fixed notary expression: reconhecimento de firma

A native speaker would recognize reconhecimento de assinatura, but reconhecimento de firma is the standard official phrase.

De here links the two nouns, like of in English.

So structurally:

• reconhecimento = recognition / verification
• de firma = of signature

This noun + de + noun pattern is extremely common in Portuguese:

• copo de água = glass of water
• sala de aula = classroom
• certidão de nascimento = birth certificate

So reconhecimento de firma is literally something like recognition/verification of signature.

É feito is a passive-style construction meaning is done.

Breakdown:

• é = is
• feito = done / made, past participle of fazer

So:

• é feito = is done

In this sentence, it expresses a general fact or procedure:

• O reconhecimento de firma é feito no cartório.
• Signature notarization is done at the notary office.

This is a very common way to describe processes in Portuguese.

Because feito agrees with reconhecimento, which is masculine singular.

Agreement in Portuguese:

• o reconhecimento → feito
• a assinatura → feita

Compare:

• O reconhecimento é feito no cartório.
• A autenticação é feita no cartório.

The participle must match the noun it refers to.

No is a contraction of:

• em + o = no

So:

• no cartório = in the notary office / at the registry office

This kind of contraction is very common in Portuguese:

• em + a = na
• de + o = do
• de + a = da

Examples:

• no banco = at the bank
• na escola = at school
• do Brasil = of/from Brazil

A cartório is a Brazilian public registry/notary office. It handles a lot of formal legal and administrative acts, such as:

• notarizing signatures
• certifying copies
• registering births, marriages, and deaths
• other official records

There is no perfect one-word equivalent in English, because the institution is very specific to Brazil and other Portuguese-speaking legal systems. Depending on context, it may be translated as:

• notary office
• registry office
• civil registry office

In this sentence, notary office is usually the best practical translation.

Yes, it functions like a passive statement.

The focus is on the procedure, not on who performs it:

• O reconhecimento de firma é feito no cartório.
• literally: The signature recognition is done at the notary office.

This is similar to English:

• The document is signed here.
• Payment is made online.

Portuguese often uses this structure in formal or procedural language.

Yes. Some possible alternatives are:

• Reconhecimento de firma é feito no cartório.
  Slightly less formal because it drops the article o, but still understandable.

• O reconhecimento de firma é realizado no cartório.
  More formal. Realizado sounds more official than feito.

• Faz-se reconhecimento de firma no cartório.
  More impersonal, a bit formal or bureaucratic.

• Firma é reconhecida no cartório.
  Grammatically possible, but less natural as the standard way to name the procedure.

The original sentence sounds very natural and standard.

It normally sounds like a general rule or standard procedure.

Because it uses the present tense:

• é feito = is done

It suggests:

• This procedure is done at the notary office
• not necessarily it was done in one specific situation

If you wanted a specific past event, you would say something like:

• O reconhecimento de firma foi feito no cartório. = The signature notarization was done at the notary office.

In Brazilian Portuguese, reconhecimento is roughly pronounced like:

heh-koh-nyeh-see-MEN-too
or more carefully: re-co-nhe-ci-men-to

A few pronunciation notes:

• nh sounds like the ny in canyon
• the stress is on men
• the final o in Brazilian Portuguese often sounds like oo

Also:

• firma ≈ FEER-ma
• cartório ≈ kar-TOH-ryoo, with stress on tó

Yes. It can be used both as a general uncountable procedure and as a countable event.

General/procedural:

• O reconhecimento de firma é feito no cartório.

One instance:

• Preciso de um reconhecimento de firma.
• I need a signature notarization.

Plural:

• Os reconhecimentos de firma foram feitos ontem.

So the expression behaves like a normal noun phrase.