Confiro o décimo terceiro e o FGTS.

In Brazilian Portuguese, subject pronouns are often omitted when the verb ending already makes the subject clear.

Confiro is the 1st person singular form, so it already means I check / I review / I verify.

So both of these are possible:

• Confiro o décimo terceiro e o FGTS.
• Eu confiro o décimo terceiro e o FGTS.

The version without eu sounds very natural and is extremely common.

Confiro is the present indicative form of the verb conferir for eu.

Conjugation:

• eu confiro
• você/ele/ela confere
• nós conferimos
• vocês/eles/elas conferem

In this sentence, confiro can mean:

• I check
• I review
• I verify

Depending on context, it can describe either a habit or something happening now.

Usually, no. This is a common false-friend issue for English speakers.

In a sentence like this, conferir usually means:

• to check
• to verify
• to review
• to make sure everything is correct

So Confiro o décimo terceiro e o FGTS is more like I check the 13th salary and the FGTS, not I confer in the formal English sense.

Here, décimo terceiro is short for décimo terceiro salário, which is a very common Brazilian term.

It refers to the 13th salary, an extra yearly payment employees typically receive in Brazil.

In everyday language, people often omit salário because the meaning is already understood:

• o décimo terceiro salário = the full form
• o décimo terceiro = the usual shorter form

It is masculine because the omitted noun is salário, which is masculine:

• o salário
• therefore o décimo terceiro salário
• and shortened: o décimo terceiro

So even when salário is left out, the article stays masculine: o.

Portuguese uses definite articles more often than English.

Here, both items are treated as specific things the speaker is checking:

• o décimo terceiro
• o FGTS

This sounds natural in Portuguese. In English, you might or might not use the, depending on context, but in Portuguese the articles are very normal here.

Because acronyms in Portuguese often take an article, especially when they refer to a noun phrase with a grammatical gender.

FGTS stands for Fundo de Garantia do Tempo de Serviço.

The key noun is fundo, which is masculine, so the acronym usually takes o:

• o FGTS

This is very common with Brazilian acronyms.

FGTS is a Brazilian labor-related fund: Fundo de Garantia do Tempo de Serviço.

Brazilians normally pronounce the acronym letter by letter, not as a single word:

• efe
• gê
• tê
• ésse

So it sounds like: efe-gê-tê-ésse.

Yes. That version is also natural, but it changes the feel slightly.

• Confiro o décimo terceiro e o FGTS.
  This can mean I check in a general, habitual, or simple present sense. Depending on context, it can also describe what you are doing now.

• Estou conferindo o décimo terceiro e o FGTS.
  This clearly emphasizes that the action is in progress right now: I am checking.

Brazilian Portuguese uses both structures, but the simple present is often a bit more flexible than English.

It could be either. The present indicative in Portuguese is flexible.

Confiro o décimo terceiro e o FGTS can mean:

• I check the 13th salary and the FGTS as part of my job or routine
• I’m checking the 13th salary and the FGTS right now, depending on context

If the speaker wants to make the ongoing action unmistakable, they can use:

• Estou conferindo o décimo terceiro e o FGTS.

Originally, décimo terceiro is an ordinal expression, basically thirteenth. In décimo terceiro salário, it works with the noun salário.

But in this sentence, it is being used as a noun phrase by itself, because salário is omitted:

• full form: o décimo terceiro salário
• shortened form: o décimo terceiro

So here it functions like a noun, even though historically it comes from an ordinal expression.