Na sexta-feira, eu vou ao centro depois do trabalho.

Na is a contraction of em + a, and it means on the here.

So:

• em a sexta-feira → na sexta-feira
• meaning: on Friday

In Brazilian Portuguese, na sexta-feira is a very common way to say on Friday.

You may also hear just sexta-feira in some contexts, but na sexta-feira is very standard and natural.

Because the word feira is feminine, and sexta-feira is built around that noun.

So it takes feminine forms:

• a sexta-feira
• na sexta-feira

The days from Monday to Friday are:

• segunda-feira
• terça-feira
• quarta-feira
• quinta-feira
• sexta-feira

They are all feminine because of feira.

Usually na sexta-feira means on Friday or this coming Friday, depending on context.

It normally refers to one specific Friday, not a repeated habit.

If you want to say every Friday, Portuguese usually uses:

• às sextas-feiras

So:

• Na sexta-feira, eu vou ao centro. = On Friday / This Friday, I’m going downtown.
• Às sextas-feiras, eu vou ao centro. = On Fridays / Every Friday, I go downtown.

Because Na sexta-feira is a time expression placed at the beginning of the sentence.

In Portuguese, it is very common to put a comma after an introductory time phrase, especially when it comes first:

• Na sexta-feira, eu vou ao centro...

This works a lot like English:

• On Friday, I’m going downtown...

The comma helps separate the time setting from the rest of the sentence.

Yes, it can be omitted.

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

So both are natural:

• Na sexta-feira, eu vou ao centro depois do trabalho.
• Na sexta-feira, vou ao centro depois do trabalho.

Since vou clearly means I go / I’m going, eu is optional.

People often include eu for:

• emphasis
• clarity
• contrast

For example:

• Eu vou ao centro, mas ela vai ao shopping.

Because Portuguese, like English, often uses the present tense to talk about a planned future event when the time is already clear.

Here, na sexta-feira gives the future time reference, so:

• Na sexta-feira, eu vou ao centro...

can naturally mean:

• On Friday, I’m going downtown...

This is very common in everyday speech.

So vou can mean:

• I go
• I’m going
• sometimes I will go

depending on context.

Ao is a contraction of a + o.

So:

• a = to
• o centro = the center / downtown
• a o centro → ao centro

That contraction is required.

So:

• vou ao centro = I go / I’m going downtown
• not vou a o centro

In Brazilian Portuguese, o centro often means:

• the city center
• downtown
• the central area of town

So vou ao centro usually means I’m going downtown or I’m going to the city center, not necessarily to a center in a general sense.

Meaning depends on context, but in everyday use this is very common.

Both can be possible, but they are used a little differently.

• ir ao centro is a very common, standard way to say to go downtown / to the city center
• ir para o centro also exists and can emphasize movement toward that destination

In many everyday situations, vou ao centro sounds very natural and idiomatic.

So for this sentence, ao centro is exactly what a learner should expect to hear.

Because do is a contraction of de + o.

So:

• de = after / of / from, depending on context
• o trabalho = work
• de o trabalho → do trabalho

Here:

• depois de = after
• depois do trabalho = after work

This kind of contraction is very common in Portuguese.

Portuguese often uses definite articles more than English does.

So where English says:

• after work

Portuguese naturally says:

• depois do trabalho

Literally, that looks like after the work, but in real usage it simply means after work.

Using the article here sounds normal and idiomatic in Portuguese.

The structure is:

• Na sexta-feira = time expression
• eu = subject
• vou = verb
• ao centro = destination
• depois do trabalho = time expression / circumstance

So the sentence is built as:

Time + Subject + Verb + Place + Time

Portuguese word order is flexible, but this order is very natural.

Yes, that is grammatically possible.

Portuguese allows some flexibility in word order, especially with time expressions.

Compare:

• Na sexta-feira, eu vou ao centro depois do trabalho.
• Depois do trabalho, eu vou ao centro na sexta-feira.

Both are understandable, but they focus slightly differently:

• starting with Na sexta-feira emphasizes when
• starting with Depois do trabalho emphasizes after what

The original sentence sounds very natural.

In Portuguese, days of the week are normally written in lowercase, unlike in English.

So:

• sexta-feira
• not Sexta-feira

This is the standard rule in Portuguese spelling.

Yes. In casual Brazilian Portuguese, people often shorten it to:

• sexta

So you may hear:

• Na sexta, eu vou ao centro.

This is very common in speech and informal writing.

The full form sexta-feira is still correct and standard.

A natural Brazilian pronunciation is approximately:

nah SEHSH-tah FEY-rah, eh-o VOH ow SEN-troo deh-POYSH doo trah-BAH-lyoo

A few helpful notes:

• sexta often sounds closer to SESH-ta or SEHSH-ta in Brazil
• ao sounds like ow
• centro has a nasal-ish quality in many accents
• trabalho has lh, which sounds like the lli in million for English speakers

Pronunciation varies by region, but this approximation is a useful start.