Eu costumo ajudar minha mãe na cozinha.

Yes, you can usually leave it out.

Portuguese often drops subject pronouns when the verb already makes the subject clear. So:

• Eu costumo ajudar minha mãe na cozinha.
• Costumo ajudar minha mãe na cozinha.

Both are natural and mean the same thing.

Including eu can add emphasis, contrast, or clarity. For example, if you want to stress I as opposed to someone else, saying eu makes sense.

Costumo comes from the verb costumar, which means to usually do something, to be in the habit of doing something, or to tend to do something.

So eu costumo ajudar means:

• I usually help
• I tend to help
• I’m used to helping in some contexts

In this sentence, the most natural English idea is I usually help my mother in the kitchen.

Both can work, but they are slightly different.

• Eu ajudo minha mãe na cozinha. = I help my mother in the kitchen.
• Eu costumo ajudar minha mãe na cozinha. = I usually help my mother in the kitchen.

Adding costumo emphasizes that this is a habit or regular action, not just a general fact.

So costumar + infinitive is a very common way to express usually do in Portuguese.

It works like this:

• costumo = conjugated verb
• ajudar = infinitive

So the pattern is:

costumar + infinitive

Examples:

• Costumo estudar à noite. = I usually study at night.
• Ela costuma correr de manhã. = She usually runs in the morning.

In your sentence:

• Eu costumo ajudar minha mãe na cozinha.

Literally, it is something like:

• I usually to-help my mother in the kitchen

But in natural English, of course, that becomes:

• I usually help my mother in the kitchen.

Here is the present tense of costumar:

• eu costumo
• você / ele / ela costuma
• nós costumamos
• vocês / eles / elas costumam

Examples:

• Eu costumo ler antes de dormir.
• Ela costuma acordar cedo.
• Nós costumamos viajar em julho.

It is a regular -ar verb.

Both are possible in Brazilian Portuguese.

You can say:

• ajudar minha mãe
• ajudar a minha mãe

The article before a possessive adjective (meu, minha, seu, nossa, etc.) is often optional in Brazilian Portuguese, especially depending on region, style, and rhythm.

So both of these are natural:

• Eu costumo ajudar minha mãe na cozinha.
• Eu costumo ajudar a minha mãe na cozinha.

Leaving out the article is very common and sounds perfectly normal.

Minha means my and agrees with the noun it describes.

Because mãe is a feminine singular noun, you use:

• minha mãe = my mother

Compare:

• meu pai = my father
• minha irmã = my sister
• meus amigos = my friends
• minhas amigas = my friends (female)

So minha is feminine singular to match mãe.

Because ajudar normally takes a direct object.

So:

• ajudar minha mãe = help my mother

You do not normally say:

• ajudar a minha mãe because of a required preposition

If you see a minha mãe, that a is usually the article, not a preposition.

This is different from some Portuguese verbs that do require prepositions. But ajudar usually does not.

Na cozinha is a contraction:

• em = in
• a = the
• em + a = na

So:

• na cozinha = in the kitchen

This contraction is extremely common in Portuguese.

Other examples:

• no carro = in the car (em + o)
• na escola = at/in the school (em + a)
• nos livros = in the books (em + os)
• nas casas = in the houses (em + as)

Because Portuguese nouns have grammatical gender, and cozinha is feminine.

So the article is a, and when combined with em, you get:

• em + a cozinha → na cozinha

If the noun were masculine, you would use no instead:

• no banheiro = in the bathroom
• no quarto = in the bedroom

Yes, depending on context, it can suggest either:

• location: in the kitchen
• activity/context: with kitchen work / while cooking / in food prep

In this sentence, na cozinha most naturally means that the help happens in the kitchen, but in real life it often also implies helping with kitchen-related tasks.

If you specifically wanted with cooking, you might say:

• Eu costumo ajudar minha mãe a cozinhar. = I usually help my mother cook.
• Eu costumo ajudar minha mãe com a comida. = I usually help my mother with the food.

No, that would sound wrong.

You need the article here:

• na cozinha = in the kitchen

Portuguese usually uses the article with this kind of place noun in a sentence like this. Since cozinha is feminine singular, em + a becomes na.

So the natural form is:

• Eu costumo ajudar minha mãe na cozinha.

The original word order is the most neutral and natural:

• Eu costumo ajudar minha mãe na cozinha.

But Portuguese does allow some flexibility.

For example:

• Costumo ajudar minha mãe na cozinha.
• Na cozinha, eu costumo ajudar minha mãe.

These alternatives are possible, but the original is the most standard everyday order.

Usually, learners should stick with: subject + verb + object + place

Mãe has a tilde: ã.

That mark shows a nasal sound. So mãe is pronounced roughly like myng or maeng, but not exactly like any normal English word. The vowel is nasal, meaning some air also goes through the nose.

Important points:

• ã is nasal
• mãe is one syllable in natural speech for many speakers, or very close to it
• it does not sound like plain mae

The tilde is important because it changes the pronunciation.

A rough pronunciation guide for English speakers is:

eh-ooh ko-STOO-moo ah-zhoo-DAR MEE-nyah MAH-ee na ko-ZEE-nyah

A few notes:

• eu often sounds like eh-ooh or yooh depending on the speaker
• ajudar has a soft j sound, like the s in measure
• minha sounds like MEE-nyah
• cozinha sounds like ko-ZEE-nyah
• mãe has that nasal vowel, which is hard to represent in English spelling

This is only an approximation, but it can help at first.

Yes, it is completely natural.

A Brazilian would easily understand it, and it sounds like normal everyday Portuguese. It is a good sentence because it uses several very common patterns:

• optional subject pronoun
• costumar + infinitive
• possessive adjective
• a common place expression with contraction: na cozinha

So this is a very useful model sentence to learn from.