Zero documentos estão prontos.

In Portuguese, zero normally takes a plural noun.

So you say:

• zero documentos
• zero pessoas
• zero reais

This is similar to how many languages treat quantities: anything other than exactly one usually goes with the plural.

So zero documento would sound wrong in standard Portuguese.

Because the subject is documentos, which is plural.

Even though the quantity is zero, Portuguese grammar still treats zero documentos as grammatically plural, so the verb must agree:

• Zero documentos estão prontos.
• Dois documentos estão prontos.
• Muitos documentos estão prontos.

If the subject were singular, the verb would be singular:

• Um documento está pronto.

Because pronto is an adjective, and in Portuguese adjectives usually agree with the noun in gender and number.

Here:

• documento = masculine singular
• documentos = masculine plural

So the adjective must also be masculine plural:

• documento pronto
• documentos prontos

If the noun were feminine, it would change:

• a pasta pronta
• as pastas prontas

Portuguese usually uses estar for a state or condition, and ser for a more permanent characteristic or identity.

Here, prontos means ready, which is a condition, so estar is the natural choice:

• Os documentos estão prontos. = The documents are ready.

Using ser with pronto is generally not what you want here.

So for learners, the safest idea is:

• estar pronto = to be ready

Yes, it is grammatical and understandable, but it can sound a bit formal, technical, or like something from a report, system message, or data summary.

In everyday Brazilian Portuguese, people often say things like:

• Nenhum documento está pronto.
• Não há documentos prontos.
• Não tem nenhum documento pronto. (very common in speech)

So your sentence is correct, but it may sound more like a count or status statement than casual conversation.

Yes, absolutely.

That is a very common and natural alternative. It means essentially the same thing, but the grammar changes:

• Nenhum documento está pronto.

Here, nenhum documento is treated as singular, so:

• documento is singular
• está is singular
• pronto is singular

Compare:

• Zero documentos estão prontos.
• Nenhum documento está pronto.

Both are correct, but nenhum documento... often sounds more natural in regular speech.

No. Zero does not change for gender in this kind of use.

You use zero with both masculine and feminine nouns:

• zero documentos
• zero páginas
• zero ideias

The noun and adjective may change, but zero itself stays the same.

Normally, no.

After numbers, Portuguese usually uses the noun directly:

• zero documentos
• dois documentos
• três documentos

So Zero documentos estão prontos is the normal structure.

You might see an article in more specific or unusual contexts, but for a basic sentence like this, no article is the standard choice.

Yes. Depending on context, pronto can mean things like:

• ready
• finished
• prepared
• done

So documentos estão prontos could mean:

• the documents are ready
• the documents are finished/prepared

The exact nuance depends on the situation. For example, in an office context, it might mean the documents have been prepared and are now available.

A simple approximate pronunciation is:

ZEH-roh doh-koo-MEN-toos es-TOWN PRON-toos

A more IPA-style version in Brazilian Portuguese is roughly:

/ˈzɛ.ɾu dokuˈmẽ.tus esˈtɐ̃w ˈpɾõ.tus/

A few helpful notes:

• r in zero is a light flap, somewhat like the American English tt in butter
• ão in estão is nasal
• pron in prontos is also nasalized

If you want to sound natural, try to say it smoothly as one phrase rather than word by word.

The normal order here is:

Zero documentos estão prontos.

That is the most straightforward and standard version.

Portuguese word order can sometimes change for style or emphasis, but with a sentence like this, the standard order is best for learners. So it is safest to keep:

• quantity + noun + verb + adjective

In other words:

• Zero documentos estão prontos.

is the version you should learn first.