Learn Hardcore Portuguese (Portugal): Nós caminhamos pelo jardim ao fim da tarde. - We walk through the garden in the late afternoon.

you want to emphasize the subject:
Nós caminhamos, eles ficam em casa. – We walk, they stay at home.
you want to contrast subjects (we vs. they, I vs. you, etc.).
you need extra clarity in a longer or more complex context.

So here Nós is optional; the sentence is perfectly fine without it.

Does caminhamos mean we walk or we walked? How can I tell the tense?

Caminhamos can mean we walk (present) or we walked (simple past).

For regular -ar verbs (like caminhar), the nós form is the same in:

Present (presente do indicativo):
(Nós) caminhamos todos os dias. – We walk every day.
Simple past (pretérito perfeito):
Ontem (nós) caminhamos pelo jardim. – Yesterday we walked through the garden.

You know which tense it is from:

time expressions:
ontem, hoje, amanhã, sempre, todos os dias, no ano passado, etc.
the wider context (what tenses are used around it, is it a story about yesterday or a routine, etc.).

If you want to make it clearly present in European Portuguese, you can also use the progressive:

Estamos a caminhar pelo jardim ao fim da tarde. – We are walking through the garden in the late afternoon.

What verb is caminhamos from, and how is it conjugated?

Caminhamos comes from the verb caminhar (to walk).

A quick look at the nós form in two key tenses:

Presente do indicativo (present):
- eu caminho
- tu caminhas
- ele / ela caminha
- nós caminhamos
- vós caminhais (rare in modern speech)
- eles / elas caminham
Pretérito perfeito (simple past):
- eu caminhei
- tu caminhaste
- ele / ela caminhou
- nós caminhamos
- vós caminhastes (rare)
- eles / elas caminharam

So the form caminhamos is shared by both tenses for nós.

What exactly does pelo mean, and why isn’t it written as por o?

Pelo is a contraction of the preposition por and the definite article o:

por + o = pelo
por + a = pela
por + os = pelos
por + as = pelas

In your sentence:

por = through / along / by (showing movement or path)
o jardim = the garden
→ pelo jardim = through the garden / along the garden

In standard European Portuguese you almost always contract por + article. Saying por o jardim instead of pelo jardim sounds very unnatural.

Could I say no jardim instead of pelo jardim? What is the difference?

You can say no jardim, but it changes the meaning.

no jardim = em + o jardim
- focuses on location: in the garden, inside the garden
- (Nós) caminhamos no jardim. – We walk in the garden.
pelo jardim = por + o jardim
- focuses on path / movement through or around the garden
- (Nós) caminhamos pelo jardim. – We walk through / around the garden.

In your sentence, pelo jardim suggests moving through the space (maybe along paths, around the flowerbeds), not just being located in the garden.

What does ao fim da tarde literally mean, and how is it different from à tarde or de tarde?

Literally, ao fim da tarde is:

ao = to / at the (a + o)
fim = end
da tarde = of the afternoon (de + a tarde)

So ao fim da tarde = at the end of the afternoon, i.e. late afternoon / towards evening.

Compare:

à tarde / de tarde
- more general: in the afternoon
- Costumamos caminhar à tarde. – We usually walk in the afternoon.
ao fim da tarde / no fim da tarde
- more specific: towards the end of the afternoon, late afternoon
- Caminhamos pelo jardim ao fim da tarde. – We walk through the garden in the late afternoon.

So your sentence is about when in the afternoon: specifically late in the afternoon, not just any time in the afternoon.

Why do we have ao and da here? Are those also contractions?

Yes, they are very common preposition + article contractions:

a + o = ao
- ao fim – at the end
de + a = da
- da tarde – of the afternoon

The full structure is:

ao fim da tarde
= a + o fim + de + a tarde

This kind of contraction is extremely frequent in Portuguese:

a + a = à → à tarde – in the afternoon
em + o = no → no jardim – in the garden
em + a = na → na rua – in the street
de + o = do → do jardim – of/from the garden

Is jardim masculine? How can I tell which article to use?

Yes, jardim is masculine:

o jardim – the garden
um jardim – a garden
os jardins – the gardens
uns jardins – some gardens

There is no 100% reliable rule for gender, but some patterns help:

Nouns ending in -im are often masculine:
o jardim (garden), o fim (end), o regime (regime).

In your sentence:

pelo jardim = por + o jardim (masculine singular article o), confirming that jardim is masculine.

Can I change the word order, for example Nós caminhamos ao fim da tarde pelo jardim?

You can change the order, but some options sound more natural than others.

The most neutral orders are:

(Nós) caminhamos pelo jardim ao fim da tarde.
Ao fim da tarde, (nós) caminhamos pelo jardim.

Time and place expressions are fairly flexible, but:

time often goes at the beginning or end;
place also often goes at the beginning or right after the verb.

Nós caminhamos ao fim da tarde pelo jardim is grammatically possible, but it sounds a bit less natural: speakers usually keep pelo jardim (place / path) closer to the verb and then add the time expression ao fim da tarde.

How do you pronounce Nós caminhamos pelo jardim ao fim da tarde in European Portuguese?

Approximate European Portuguese pronunciation:

Nós – like nosh (short vowel, final s often like English sh)
caminhamos – kah-min-YAH-moosh (final -mos often sounds like -moosh)
pelo – PEH-loo (very short vowels)
jardim – zhar-DEENG (j like French j in je, final m nasalizes the vowel)
ao – roughly ow as in cow
fim – feeng (again, nasal vowel)
da – dah
tarde – TAR-d(ɨ) (final e is very reduced, almost like a soft uh)

Spoken smoothly, it might sound like:

[nosh kah-min-YAH-moosh PEH-loo zhar-DEENG ow FEENG dah TAR-dɨ]

Key pronunciation points:

nh in caminhamos is like Spanish ñ in niño.
j in jardim is like French j in jour, not like English j in jam.
Final m (in jardim, fim) makes the vowel nasal; the m itself is not fully pronounced.
Many final consonants, like -s and -e, are softened or reduced in European Portuguese.

Is there a difference between this sentence in European and Brazilian Portuguese?

The sentence itself is grammatically correct and understandable in both varieties:

Nós caminhamos pelo jardim ao fim da tarde.

Differences you might notice:

Choice of expression for time
- European Portuguese: ao fim da tarde is very natural.
- Brazilian Portuguese: no fim da tarde or no final da tarde are more common in everyday speech, though ao fim da tarde is still correct.
Progressive form
- European: Estamos a caminhar pelo jardim ao fim da tarde.
- Brazilian: Estamos caminhando pelo jardim no fim da tarde.
Pronunciation is quite different (Brazilian Portuguese has more open, clearer vowels and usually pronounces final consonants more fully), but the written sentence is shared.

Could I use andar instead of caminhar here? Is there a difference?

Yes, you could say:

Nós andamos pelo jardim ao fim da tarde.

Both andar and caminhar can mean to walk, but:

andar is more common in everyday European Portuguese for ordinary walking:
- Ando muito a pé. – I walk a lot / I go on foot a lot.
caminhar often sounds:
- a bit more deliberate (going for a walk, for exercise), or
- a bit more formal / literary, especially in figurative uses:
  - Caminhamos juntos pela vida. – We walk together through life.

In your sentence, both are correct.
Caminhamos might suggest more of a purposeful walk, maybe a regular stroll; andamos often feels more casual/colloquial.

What exactly does ao fim da tarde contribute, given that English might just say “in the afternoon”?

Ao fim da tarde is more specific than just “in the afternoon”.

in the afternoon (English) could be any time after lunch and before evening.
ao fim da tarde narrows it to late afternoon, towards the end of that period.

So the Portuguese sentence suggests a more precise time window: not just sometime in the afternoon, but near the end of it.