Ao fim da tarde, eu caminho pela cidade com o Pedro.

It means at the end of the afternoon, often more naturally in English in the late afternoon or towards evening.

In European Portuguese, this is a very normal time expression. It sets the scene before the main part of the sentence.

Because ao is the contraction of a + o:

• a = to / at
• o = the

So:

• a + o fim → ao fim

This kind of contraction is extremely common in Portuguese.

Da is the contraction of de + a:

• de = of
• a = the

So:

• de + a tarde → da tarde

Literally, ao fim da tarde is at the end of the afternoon.

Yes, but the difference is small.

• ao fim da tarde often feels like towards the end of the afternoon
• no fim da tarde means in/at the end of the afternoon

In many everyday contexts, they are very close and can often both be used. In this sentence, ao fim da tarde sounds very natural.

Because Ao fim da tarde is an introductory time phrase.

Portuguese often uses a comma after a time expression placed at the beginning of the sentence, especially in careful writing. It helps separate the setting from the main clause:

• Ao fim da tarde, eu caminho pela cidade com o Pedro.

You could also say:

• Eu caminho pela cidade com o Pedro ao fim da tarde.

That version is also correct, just with a different rhythm.

That’s right: Portuguese often drops subject pronouns because the verb ending already shows the person.

So this sentence could also be:

• Ao fim da tarde, caminho pela cidade com o Pedro.

That is perfectly natural.

Including eu can add:

• emphasis
• clarity
• contrast

For example, if you were contrasting yourself with someone else, eu would be especially useful.

Caminho is the 1st person singular present tense of caminhar:

• eu caminho = I walk

Depending on context, the Portuguese present can sometimes correspond to English:

• I walk
• I am walking

But without extra context, this sentence often sounds more like a general or habitual action: I walk around the city with Pedro in the late afternoon.

It could be, but it changes the feel.

In European Portuguese:

• eu caminho = simple present, often habitual or general
• estou a caminhar = I am walking, specifically ongoing right now

So:

• Ao fim da tarde, eu caminho pela cidade com o Pedro.
  = more general / habitual / descriptive

• Ao fim da tarde, estou a caminhar pela cidade com o Pedro.
  = specifically describes an action in progress

In Portugal, the normal progressive form is estar a + infinitive, not the Brazilian-style estar + gerund.

Yes, but there is a nuance.

• caminhar = to walk
• andar = to walk / to go around / to move about

In many contexts, andar is more common in everyday speech, but caminhar is a bit more specific and clearly means to walk.

So:

• eu caminho pela cidade = I walk through/around the city
• eu ando pela cidade = I go/walk around the city

Both are possible, but caminho is slightly more explicit.

Pela cidade means through the city or around the city, depending on context.

Here, it suggests movement within the city, not just being located there.

So it is different from:

• na cidade = in the city

Compare:

• Estou na cidade. = I am in the city.
• Caminho pela cidade. = I walk through/around the city.

Because pela is the contraction of por + a:

• por = through / by / around
• a = the

So:

• por + a cidade → pela cidade

This is another very common Portuguese contraction.

Related forms:

• pelo = por + o
• pelos = por + os
• pelas = por + as

Because in European Portuguese it is very common to use the definite article before a person’s first name:

• o Pedro
• a Maria

So com o Pedro is completely normal in Portugal.

This is one of the things that often sounds unusual to English speakers, because English usually says just Pedro, without the.

Important note:

• In European Portuguese, this use of the article is very common.
• In some other varieties or contexts, the article may be omitted more often.

Yes. Portuguese allows some flexibility, especially with time expressions.

For example, all of these are possible:

• Ao fim da tarde, eu caminho pela cidade com o Pedro.
• Eu caminho pela cidade com o Pedro ao fim da tarde.
• Ao fim da tarde, caminho pela cidade com o Pedro.

They all mean basically the same thing, but the emphasis and rhythm change slightly.

The original version is very natural because it starts by giving the time frame.