Guardei o comprovativo.

Guardei is the 1st person singular form of the verb guardar in the pretérito perfeito (simple past / preterite).

So it means:

• I kept
• I saved
• I put away
• I stored

In this sentence, the most natural sense is something like I kept / saved the receipt/proof.

In Portuguese, the subject pronoun is often omitted when the verb already makes the subject clear.

• Guardei already tells us the subject is I
• so Eu guardei o comprovativo is possible, but Eu is not necessary

You would usually add eu only for emphasis, contrast, or clarity.

For example:

• Guardei o comprovativo. = I kept the receipt/proof.
• Eu guardei o comprovativo, não foi ele. = I kept it, not him.

It is the pretérito perfeito do indicativo.

In European Portuguese, this tense is commonly used for a completed action in the past.

So Guardei o comprovativo means that the action of keeping/saving it is finished.

Compare:

• Guardo o comprovativo. = I keep / I am keeping the receipt
• Guardei o comprovativo. = I kept / saved the receipt
• Guardava o comprovativo. = I used to keep / was keeping the receipt

O is the masculine singular definite article, meaning the.

So:

• o comprovativo = the proof / the receipt / the confirmation document

Portuguese uses definite articles more often than English does. In this sentence, it sounds natural to include o because you are referring to a specific document.

Without the article, Guardei comprovativo, it would sound unnatural in standard Portuguese.

Comprovativo is a noun meaning a document that proves something.

Depending on context, it can mean:

• receipt
• proof
• voucher
• confirmation slip
• supporting document

For example, it could be:

• proof of payment
• a receipt from a machine
• confirmation of a transfer
• a document used to show that something happened

So the exact English translation depends on context.

Yes. In European Portuguese, comprovativo is very common, especially in formal or administrative contexts.

You may hear things like:

• comprovativo de pagamento = proof of payment
• comprovativo de morada = proof of address
• comprovativo de transferência = transfer receipt / proof of transfer

A native speaker in Portugal would find Guardei o comprovativo completely natural.

Yes, often.

In Portugal, comprovativo is very common.
In Brazil, people often use comprovante instead.

So:

• European Portuguese: Guardei o comprovativo.
• Brazilian Portuguese: Guardei o comprovante.

Both refer to a document that proves something, but comprovativo sounds especially European Portuguese.

Yes, comprovativo is masculine singular here.

You can tell because it takes the article o:

• o comprovativo = masculine singular

Its plural would be:

• os comprovativos

If you see adjectives with it, they would also normally agree in the masculine form:

• o comprovativo original
• os comprovativos originais

In European Portuguese, it sounds approximately like:

gwar-DAY oo kom-proo-va-TEE-voo

A more careful approximation is:

• Guardei → the guei part sounds a bit like gay
• o → often reduced, almost like a quick u
• comprovativo → stress on ti: com-pro-va-TI-vo

A rough IPA version would be:

[ɡwɐɾˈðɐj u kõpɾuvɐˈtivu]

A few pronunciation notes:

• r in guardar is not the English r
• unstressed vowels in European Portuguese are often reduced
• the final o often sounds closer to u than a full English oh

Yes, absolutely.

Both are correct:

• Guardei o comprovativo.
• Eu guardei o comprovativo.

The version without eu is more neutral and natural in many situations.
The version with eu adds emphasis, contrast, or clarity.

So unless you need to stress I, the shorter version is usually preferred.

Yes, but the original order is the most normal one.

Standard neutral order:

• Guardei o comprovativo.

You might change the order for emphasis, but that is less neutral:

• O comprovativo, guardei-o. = The receipt, I kept it.
  This is more marked and less common in everyday speech.

For a learner, the best pattern to remember is:

verb + article + noun
Guardei o comprovativo.

Yes. Guardar is a flexible verb.

Depending on context, it can mean:

• to keep
• to save
• to put away
• to store

So Guardei o comprovativo could mean:

• I kept the receipt
• I saved the proof
• I put the receipt aside

If you are talking about a digital file or email, save may be a very natural translation. If it is a paper document, kept is often the best choice.

Sometimes yes, but they are not always identical.

• recibo usually means receipt
• comprovativo is broader: proof / receipt / supporting document

So if you specifically mean a receipt, recibo may work:

• Guardei o recibo. = I kept the receipt.

But if the document is not exactly a receipt—maybe a bank transfer confirmation or some other proof—then comprovativo is better.

So comprovativo is the safer, more general word.

You would usually say:

• Guardei o comprovativo de pagamento.

Here:

• comprovativo = proof/document
• de pagamento = of payment

This is a very common expression in European Portuguese.

Other similar examples:

• comprovativo de morada = proof of address
• comprovativo de transferência = proof of transfer
• comprovativo de inscrição = proof of registration

So the sentence you were given can also be seen as a shorter version where the exact type of proof is understood from context.