O oleiro acaba de iniciar a cozedura.

Yes, by itself acabar often means to finish or to end.

But acabar de + infinitive is a fixed expression in Portuguese that means to have just done something.

So:

• acaba de iniciar = has just started / has just begun
• literally, it is not understood word by word as finishes of starting
• it works as one grammatical pattern: acabar de + verb

Examples:

• Acabo de chegar. = I’ve just arrived.
• Ela acaba de sair. = She has just left.

So in your sentence, the meaning is:

• O oleiro acaba de iniciar a cozedura. = The potter has just started the firing.

This is a very common point of confusion.

In Portuguese, acabar de + infinitive often uses the present tense to express a very recent past.

So:

• acaba de iniciar literally looks present
• but the full construction means has just started

This is normal and idiomatic in Portuguese.

A useful way to think of it:

• present tense of acabar + de + infinitive = have/has just + past participle in English

More examples:

• Acabo de comer. = I’ve just eaten.
• Acabamos de chegar. = We’ve just arrived.

Because the structure is fixed: acabar de + infinitive.

You cannot normally say:

• acaba iniciar

You need:

• acaba de iniciar

So the pattern is:

• acabar de fazer
• acabar de chegar
• acabar de começar
• acabar de iniciar

It is best to learn acabar de as one chunk.

Oleiro means potter — someone who makes pottery.

It is a masculine noun:

• o oleiro = the potter

The feminine form is:

• a oleira = the female potter

This word is more specific than a general craftsperson: it refers to someone working with clay pottery.

Here, cozedura refers to the firing or baking process of the pottery, usually in a kiln.

It comes from the verb cozer, which can mean to cook, to boil, to bake, or in technical contexts to fire.

In a pottery context, a cozedura is not ordinary cooking. It means the stage where the clay pieces are heated so they harden.

So in this sentence:

• iniciar a cozedura = to begin the firing process

Portuguese often uses the definite article where English might not.

So:

• iniciar a cozedura

is perfectly natural and means:

• to begin the firing
• to begin the firing process

The article a shows that this is a specific process understood in the context.

English often drops the article in similar situations, but Portuguese frequently keeps it.

They are very close, but not always identical in tone.

• começar = to start, to begin
• iniciar = to initiate, to begin

In many contexts they can replace each other:

• O oleiro acaba de começar a cozedura.
• O oleiro acaba de iniciar a cozedura.

But iniciar often sounds:

• slightly more formal
• a bit more technical
• a little more impersonal or precise

In this sentence, iniciar a cozedura sounds quite natural because pottery firing is a defined process.

You could, but the meaning would shift slightly.

Compare:

• O oleiro começou a cozedura. = The potter started the firing.
• O oleiro acaba de iniciar a cozedura. = The potter has just started the firing.

The second sentence emphasizes that it happened very recently.

So acaba de iniciar adds the idea of just now.

Here, O is the definite article the.

• O oleiro = the potter

It is not the pronoun he in this sentence.

Portuguese does have o as an object pronoun in some contexts, but not here. Because it comes directly before the noun oleiro, it is clearly the article.

A rough European Portuguese pronunciation is:

o oleiro acaba de iniciar a cozedura
≈ oo oo-LAY-roo uh-KAH-buh d(uh) ee-nee-syar uh koo-zuh-DOO-ruh

A few helpful notes:

• oleiro sounds roughly like oo-LAY-roo
• acaba has a reduced final vowel in European Portuguese
• iniciar sounds roughly like ee-nee-syar
• cozedura has a z sound in the middle: koo-zuh-DOO-ruh

If you want a more IPA-style version, a broad approximation is:

• [u uˈlejɾu ɐˈkabɐ dɨ iniˈsjaɾ ɐ कु?]

To avoid giving you a misleadingly narrow transcription, the rough pronunciation guide above is probably more useful at this stage.

It is understandable, but it is not one of the most everyday words in casual conversation.

In this kind of sentence, it sounds:

• correct
• somewhat technical
• appropriate for a pottery or craft context

In ordinary food-related contexts, other words may be more common depending on the meaning. But for pottery, cozedura works well to refer to the firing/baking stage.

The structure is:

• O oleiro = subject
• acaba de iniciar = verb phrase
• a cozedura = direct object

So:

[Subject] + [acabar de + infinitive] + [object]

More examples with the same pattern:

• A professora acaba de entrar na sala. = The teacher has just entered the room.
• Os alunos acabam de terminar o exercício. = The students have just finished the exercise.

In your sentence, the grammar is very straightforward once you recognize acabar de + infinitive as one unit.