O vencedor recebeu o prémio.

Because o is the masculine singular definite article, meaning the.

• O vencedor = the winner
• o prémio = the prize

English uses the for both subject and object too, so this is quite similar. Portuguese articles change for gender and number:

• o = masculine singular
• a = feminine singular
• os = masculine plural
• as = feminine plural

So both vencedor and prémio are masculine singular nouns, which is why both use o.

Recebeu is the 3rd person singular of the pretérito perfeito simples, which is the normal past tense for a completed action.

It comes from the verb receber = to receive.

So:

• eu recebi = I received
• tu recebeste = you received
• ele/ela/você recebeu = he/she/you received

In this sentence, recebeu means received.

Because recebeu describes a completed event: the winner received the prize.

Compare:

• recebeu = received / got it at a specific moment
• recebia = used to receive, was receiving, or would receive depending on context

So O vencedor recebeu o prémio sounds like a finished action, for example after a competition or ceremony.

Its most common meaning is winner, but it can also mean victor or victorious one, depending on context.

Examples:

• o vencedor do concurso = the winner of the contest
• o exército vencedor = the victorious army

In your sentence, the natural meaning is simply the winner.

You usually learn the gender together with the noun:

• o vencedor
• o prémio

Sometimes word endings help, but they are not perfect rules.

• Nouns ending in -or are often masculine: o vencedor, o professor
• prémio is masculine, so it takes o

The safest method is to learn each noun with its article, not by itself.

The accent in prémio shows which syllable is stressed and also helps show the vowel quality.

In European Portuguese, prémio is stressed like this:

• PRÉ-mio

The accent marks the stressed é.

This is also a useful spelling difference between European and Brazilian Portuguese:

• Portugal: prémio
• Brazil: prêmio

Both mean prize.

Roughly like PREH-myoo, with the stress on the first syllable.

A simple learner-friendly approximation is:

• PRÉ-mio

A few notes:

• pré has an open e sound
• mio is said as part of the second syllable
• In European Portuguese, unstressed vowels are often reduced more than in English

You do not need to pronounce it exactly like English premium. It is shorter and more compact.

A broad learner-friendly approximation is:

u ven-se-DOR re-se-BEU u PRE-miu

A few pronunciation notes:

• O often sounds like u in European Portuguese when unstressed.
• vencedor is stressed on the last syllable: ven-ce-DOR
• recebeu is stressed on the last syllable: re-ce-BEU
• prémio is stressed on the first syllable: PRÉ-mio

In natural European Portuguese, unstressed vowels are often reduced, so the sentence may sound more compressed than you expect from the spelling.

This is the normal Portuguese word order:

subject + verb + object

So:

• O vencedor = subject
• recebeu = verb
• o prémio = object

This is exactly like English:

• The winner received the prize

Portuguese can sometimes change word order for style, emphasis, or in literary language, but this version is the most neutral and standard.

Yes, absolutely. That is also natural.

• recebeu o prémio = received the prize
• ganhou o prémio = won the prize

The difference is slight:

• ganhou focuses more on winning
• recebeu focuses more on receiving or being awarded it

In many real situations, both are possible, but they are not always identical in emphasis.

Not in normal standard Portuguese for this sentence.

Portuguese uses articles more often than English, and here the natural sentence is:

• O vencedor recebeu o prémio

Without the articles, it sounds unnatural or incomplete in ordinary usage.

O vencedor is doing the action.

So grammatically:

• O vencedor = subject
• recebeu = verb
• o prémio = direct object

This means the winner is the one who received, and the prize is the thing that was received.

Yes. Recebeu is the same form for all of these:

• ele recebeu = he received
• ela recebeu = she received
• você recebeu = you received

In your sentence, the subject is not a pronoun but a noun phrase:

• O vencedor recebeu...

So it works like ele recebeu...

If the winner is female, Portuguese normally uses the feminine form:

• A vencedora recebeu o prémio.

So:

• vencedor = male winner / masculine form
• vencedora = female winner / feminine form

The article changes too:

• o vencedor
• a vencedora

It is neutral standard Portuguese.

It would fit naturally in:

• news reports
• school exercises
• formal writing
• everyday speech

There is nothing especially formal or informal about it. It is just a clear, standard sentence.