Minha mãe vai temperar o frango, e eu vou mexer o arroz enquanto ele cozinha.

Because mãe is a feminine noun, so the possessive has to match it.

• meu pai = my father
• minha mãe = my mother

In Portuguese, possessives usually agree with the thing possessed, not with the speaker.

Yes. In Brazilian Portuguese, both minha mãe and a minha mãe are possible.

• Minha mãe vai temperar o frango
• A minha mãe vai temperar o frango

Adding the article a is very common in Brazil, especially in everyday speech. Leaving it out is also correct.

Vai temperar is the structure ir + infinitive, which is one of the most common ways to talk about the future in Brazilian Portuguese.

• vai temperar = is going to season
• vou mexer = I am going to stir

It is very similar to English be going to + verb.

Because this is a new clause with a new subject: eu.

The sentence has two separate future actions:

• Minha mãe vai temperar o frango
• eu vou mexer o arroz

You cannot normally say e eu mexer o arroz here. The future meaning needs the full structure vou + infinitive.

In cooking, temperar usually means to season food.

It can include things like:

• adding salt
• adding garlic, pepper, herbs, or spices
• sometimes marinating, depending on context

So here temperar o frango means something like season the chicken.

Here mexer o arroz means to stir the rice.

Mexer often means:

• to move
• to stir
• to handle

It is not exactly the same as misturar:

• mexer = stir or move around
• misturar = mix or combine

Also, mexer no arroz can sound more like mess with the rice or touch the rice, while mexer o arroz is the more direct cooking meaning in this sentence.

Portuguese uses definite articles very often, especially when talking about specific things already understood in the situation.

So:

• o frango = the chicken
• o arroz = the rice

In this sentence, it is clear that they mean the chicken and rice they are preparing. Without the articles, it could sound more general, like talking about chicken or rice as a category.

Enquanto means while.

It introduces an action happening at the same time as another action.

In this sentence:

• eu vou mexer o arroz = one action
• enquanto ele cozinha = happening at the same time

So enquanto connects the two simultaneous actions.

Ele refers to o arroz.

Because arroz is a masculine noun, the pronoun that refers back to it is ele.

Even though English uses it for things, Portuguese often uses ele or ela based on grammatical gender.

So here:

• o arroz → ele
• translation in English: it

Yes, it is grammatically correct. Portuguese nouns have grammatical gender, so pronouns can agree with them.

That said, many speakers might also avoid the pronoun and simply repeat the noun:

• enquanto o arroz cozinha

That can sound a little more natural in some contexts. But enquanto ele cozinha is still understandable and correct.

Because in Portuguese, the simple present often works where English might use either cooks or is cooking.

So:

• ele cozinha can mean it cooks or it is cooking, depending on context

In time clauses with words like enquanto, the simple present is very common and natural:

• enquanto ele cozinha = while it cooks / while it is cooking

Enquanto ele está cozinhando is also possible, but it sounds heavier here.

Yes.

• a cozinha = the kitchen
• ele cozinha = he/it cooks

The word can be either a noun or a verb form. In this sentence, it is clearly a verb because it comes after ele and describes an action.

The comma is acceptable because the sentence joins two full clauses with different subjects:

• Minha mãe vai temperar o frango
• eu vou mexer o arroz

In Portuguese, a comma before e is often optional in cases like this. Many people would also write the sentence without the comma.

So both of these can be fine:

• Minha mãe vai temperar o frango e eu vou mexer o arroz...
• Minha mãe vai temperar o frango, e eu vou mexer o arroz...

Mãe has a nasal sound because of ã.

A helpful approximation is to think of something a bit like English my, but with the vowel pronounced through the nose. It is not an exact English sound.

Important points:

• the ã is nasal
• the word is one syllable
• the tilde ~ marks nasality

This nasal vowel is one of the sounds English speakers usually need time to get used to.