No fim de semana, eu uso chinelo no quintal e tênis na rua.

Because no is a contraction of em + o.

• em = in/on/at
• o = the
• no = em o

So no fim de semana literally comes from em o fim de semana.

In natural Portuguese, people almost always use the contraction:

• no quintal = em o quintal
• na rua = em a rua

Also, no fim de semana is a very common way to say on the weekend or at the weekend in Brazilian Portuguese.

Yes, you could. Portuguese often drops subject pronouns when the verb already makes the subject clear.

• eu uso = I use / I wear
• uso by itself already tells you the subject is I

So both are natural:

• No fim de semana, eu uso chinelo no quintal e tênis na rua.
• No fim de semana, uso chinelo no quintal e tênis na rua.

Including eu can add clarity, emphasis, or contrast. For example, if you want to stress I as opposed to someone else, eu is more likely to appear.

Portuguese often uses footwear words in the singular to refer to a pair as a category of item.

So:

• uso chinelo = I wear flip-flops / slippers
• uso tênis = I wear sneakers

This is very normal in Brazilian Portuguese. You are not talking about one single flip-flop; you are talking about that type of footwear in general.

You may also hear plurals in other contexts, especially when referring to actual physical pairs or multiple items, but in general statements like this, the singular is very common.

Because tênis is one of those nouns whose singular and plural have the same form.

So:

• um tênis can mean one sneaker
• uns tênis can mean some sneakers
• very often tênis refers to a pair of sneakers in everyday usage

In this sentence, uso tênis means I wear sneakers. It is understood as the type of footwear, not necessarily one individual shoe.

This can feel odd to English speakers at first, but it is completely normal in Brazilian Portuguese.

These words refer to different kinds of footwear:

• chinelo: usually flip-flops or very casual slip-on house/outdoor footwear
• sandália: sandals
• tênis: sneakers / trainers

In Brazil, chinelo very often makes people think of simple flip-flops, the kind you might wear at home, in the yard, at the beach, or for casual errands.

So chinelo no quintal sounds very natural: casual footwear in the yard.

Because the preposition em combines with different definite articles:

• em + o = no
• em + a = na

And the nouns have different grammatical genders:

• quintal is masculine: o quintal
• rua is feminine: a rua

So:

• no quintal = in the yard
• na rua = in/on the street

This is one of the most common contraction patterns in Portuguese.

Because here the speaker is talking about footwear in a general, habitual way, not about a specific pair.

• uso chinelo = I wear flip-flops / I use flip-flops in general
• uso tênis = I wear sneakers in general

If you say uso o chinelo or uso os tênis, it sounds more like you are referring to a specific item or pair already known in the conversation.

Compare:

• No fim de semana, uso chinelo. = On weekends, I wear flip-flops.
• No fim de semana, uso o chinelo que comprei ontem. = On weekends, I wear the flip-flops I bought yesterday.

So the article is omitted because the meaning is general and habitual.

Yes, fim de semana is very common and natural in Brazil.

You will also hear final de semana in many places. Both exist, but fim de semana is often considered the more standard and widely expected form.

So for learners, fim de semana is an excellent default choice.

Yes. In Portuguese, usar is very commonly used for things you wear.

So:

• usar chinelo
• usar tênis
• usar camisa
• usar óculos

All of these are natural.

Portuguese also has more specific verbs in some contexts, such as calçar for footwear, but usar is very common and easy to use in everyday speech.

For example:

• Eu uso tênis. = very natural
• Eu calço tênis. = also possible, but a bit more specific and less universally used in casual conversation

For a learner, usar is a very useful default verb.

Because Portuguese often puts time expressions at the beginning to set the scene.

So:

• No fim de semana, eu uso chinelo no quintal e tênis na rua.

is very natural.

You could also say:

• Eu uso chinelo no quintal e tênis na rua no fim de semana.

But the original version sounds smoother and more typical because it tells you the time frame first.

This is similar to English sentences like:

• On weekends, I wear flip-flops in the yard and sneakers on the street.

Literally, na rua is in/on the street, but in real usage it can have a broader sense.

Depending on context, na rua can mean:

• on the street
• outside
• out and about
• in public spaces away from home

In this sentence, tênis na rua suggests the speaker wears sneakers when going out, walking around outside, or being on the street rather than staying in the yard.

So it is not just a strict physical location; it can also reflect the everyday contrast between at home / in the yard and out in the street / outside.