Learn Hardcore Portuguese (Portugal): Este documento oficial é muito importante. - This official document is very important.

este – this, close to the speaker
- Este documento oficial… = this official document (the one I’m holding / just mentioned / about to mention)
esse – that, closer to the listener or just mentioned
- Esse documento oficial… = that official document (near you, or the one you just referred to)
aquele – that (over there), far from both speaker and listener, or more distant in time/abstract
- Aquele documento oficial… = that official document over there / from long ago / in a previous context

In actual European Portuguese usage, the este / esse / aquele distinction is sometimes blurred in everyday speech, but the textbook rule is as above.

Why is there no article (o) before este documento oficial?

In Portuguese, demonstratives like este / essa / aquele normally replace the definite article, they don’t combine with it:

o documento = the document
este documento = this document (not o este documento)

So, in Este documento oficial é muito importante, este already does the job of “the/this”, so you don’t add o.

With possessives, you often do use an article (especially in European Portuguese):

o meu documento = my document

But with este, you don’t:

este documento (not o este documento).

Why is it documento oficial and not oficial documento?

In Portuguese, most descriptive adjectives normally come after the noun:

documento oficial = official document
casa grande = big house
livro interessante = interesting book

Putting the adjective before the noun is possible but usually:

adds emphasis, or
can slightly change the nuance or meaning.

For oficial, the natural, neutral order is documento oficial.
Oficial documento would sound poetic, marked, or odd in normal speech.

Why are este and documento masculine? How would the sentence change for a feminine noun?

Documento is a masculine noun in Portuguese (it ends in -o, which is very often masculine), so any words that agree with it take masculine forms:

este documento oficial (this official document)

If the noun were feminine, for example carta (letter), everything that needs to agree would change:

Esta carta oficial é muito importante.
- esta (feminine singular, matching carta)
- carta (feminine noun)
- oficial (adjective in -al doesn’t change in gender)
- importante (adjective in -e doesn’t change in gender)

So in this sentence:

este agrees in gender and number with documento (masculine singular).
oficial and importante end in -l and -e, so they don’t change for gender, only for number (singular/plural).

What does oficial mean here? Is it a false friend with English official?

In this context, oficial is a direct cognate of official, and the meaning is the same:

documento oficial = official document
(issued or recognized by an authority)

So it is not a false friend here. Other common uses:

língua oficial = official language
feriado oficial = official public holiday

Just note that oficial can also mean officer in some contexts, especially military, but here it clearly means official (adjective).

Why is the verb é used and not está?

Portuguese distinguishes between:

ser (used with é) – for permanent, defining, or inherent characteristics.
estar (used with está) – for temporary states, conditions, locations.

In Este documento oficial é muito importante:

Being muito importante is seen as an inherent / defining property of this official document.
It’s not just temporarily important right now; it’s important by nature or in general.

So ser (é) is the correct verb.
Este documento oficial está muito importante would sound wrong or very odd in standard Portuguese.

What is é grammatically, and what are the other forms of ser?

É is:

the 3rd person singular,
present tense,
of the verb ser (to be).

So it corresponds to:

ele/ela é = he/she/it is
o documento é = the document is

Present tense of ser (European Portuguese):

eu sou – I am
tu és – you are (singular, informal)
ele / ela / você é – he / she / you are
nós somos – we are
vós sois – you are (archaic / liturgical)
eles / elas / vocês são – they / you (plural) are

Also, the accent in é distinguishes it from e (without accent), which means and.

How does muito work in muito importante, and why doesn’t it change form here?

Muito can be two different things:

Adverb = very / really / extremely
- Comes before an adjective or another adverb
- Does not change for gender or number
In the sentence:
- muito importante = very important
- Here, muito is an adverb modifying the adjective importante, so it stays muito in all cases:
  - muito importante (masc. sing.)
  - muito importante (fem. sing.)
  - muito importantes (masc. plural)
  - muito importantes (fem. plural)
Adjective / determiner = much / many / a lot of
- Comes before a noun
- Does change for gender and number: muito / muita / muitos / muitas
Examples:
- muito dinheiro = a lot of money (masc. sg.)
- muita informação = a lot of information (fem. sg.)
- muitos documentos = many documents (masc. pl.)
- muitas cartas = many letters (fem. pl.)

In Este documento oficial é muito importante, muito is an invariable adverb meaning very.

How does the adjective importante behave with gender and number?

Adjectives that end in -e in Portuguese:

are the same for masculine and feminine in the singular
add -s in the plural for both genders

So:

masculine singular: importante
- documento importante (important document)
feminine singular: importante
- carta importante (important letter)
masculine plural: importantes
- documentos importantes
feminine plural: importantes
- cartas importantes

In the sentence, importante is masculine singular, agreeing in number (singular) with documento, but it doesn’t show gender difference because of the -e ending.

How would you make this sentence plural?

You need to make every word that agrees with documento plural:

documento → documentos
este → estes
é (ser, 3rd person singular) → são (3rd person plural)
oficial → oficiais (plural of adjectives in -al)
importante → importantes

So the plural sentence is:

Estes documentos oficiais são muito importantes.
= These official documents are very important.

How do you pronounce Este documento oficial é muito importante in European Portuguese?

A careful, slow pronunciation (European Portuguese) can be broken down like this (approximate English-like hints):

Este → roughly like “ESH-tɨ”
- es = “esh” (like esh in fresh)
- final -e is a weak sound, like a very short “uh” or “ɨ”
documento → roughly “doo-koo-MEN-too”
- stress on MEN
oficial → roughly “oo-fee-see-AL”
- stress on AL
é → “eh” (short, open “e”, not like English “ay”)
muito → in Portugal often “MUY-tu” (with a quick “y” sound), sometimes closer to “MOOY-tu”
importante → roughly “im-por-TAN-tɨ”
- stress on TAN (with a nasalized “an”)
- final -te again with a weak “tɨ” sound

Spoken more naturally, many vowels reduce, and words link together:

[ˈeʃ.tɨ ðu.kuˈmẽ.tu u.fi.siˈaɫ ɛ ˈmuj.tu ĩ.puɾˈtɐ̃.tɨ] (approximate IPA for European Portuguese)

Could I also say Este é um documento oficial muito importante? What is the difference?

Yes, you can say:

Este é um documento oficial muito importante.
= This is a very important official document.

Difference in structure and focus:

Este documento oficial é muito importante.
- Subject: this official document
- Structure: [Este documento oficial] é [muito importante].
- Focus: Describes the document’s importance.
Este é um documento oficial muito importante.
- Subject: this (possibly something you’re pointing at)
- Structure: [Este] é [um documento oficial muito importante].
- Focus: Identifies what “this” is and characterizes it.

In many practical contexts the meaning is very close, but grammatically:

First version = statement about the document.
Second version = statement identifying what “this” is.