Quando faz sol, eu gosto de fazer exercício no parque.

This is an idiomatic weather expression in Portuguese. The verb fazer is often used for weather conditions:

• faz sol = it’s sunny
• faz frio = it’s cold
• faz calor = it’s hot

Literally, faz sol looks like it makes sun, but you should learn it as a fixed expression meaning the sun is out / it’s sunny.

Notice that there is no spoken subject like it here. Portuguese often uses weather expressions without a subject.

Because Portuguese does not normally use ser for this kind of weather statement.
For weather, Brazilian Portuguese commonly uses:

• fazer for conditions: faz sol, faz calor, faz frio
• estar with adjectives in some cases: está quente, está frio

So é sol would sound wrong here. If you want to say when it’s sunny, quando faz sol is the natural expression.

Quando means when.

In this sentence, it introduces a time condition or repeated situation:

• Quando faz sol, eu gosto de fazer exercício no parque.
• When it’s sunny, I like to exercise in the park.

It does not mean one single event only. In the present tense, it often suggests a general habit: whenever it’s sunny.

The comma separates the introductory time clause from the main clause.

• Quando faz sol, = introductory clause
• eu gosto de fazer exercício no parque. = main clause

This is very similar to English:

• When it’s sunny, I like to exercise in the park.

In Portuguese, this comma is natural and standard when the subordinate clause comes first.

Yes, you can.

Brazilian Portuguese often includes subject pronouns like eu, but it can also omit them when the meaning is clear from context.

So both are correct:

• Quando faz sol, eu gosto de fazer exercício no parque.
• Quando faz sol, gosto de fazer exercício no parque.

Including eu can add emphasis, clarity, or simply sound more natural in some contexts.

Because the verb gostar requires the preposition de before what is liked.

So you say:

• gosto de café
• gosto de música
• gosto de correr
• gosto de fazer exercício

This is an important pattern to memorize:

• gostar de + noun
• gostar de + infinitive

So gosto fazer is incorrect.

They are the same verb, but in different forms:

• faz = third person singular present of fazer
• fazer = infinitive, meaning to do / to make

In the sentence:

• Quando faz sol → faz is a conjugated verb in the weather expression
• gosto de fazer exercício → fazer stays in the infinitive after gosto de

So the sentence contains:

1. a conjugated verb for the situation: faz
2. an infinitive for the activity liked: fazer exercício

Both are possible, but fazer exercício is very common and natural in Brazilian Portuguese.

Common options include:

• fazer exercício = to exercise / to do exercise
• me exercitar = to exercise

So these are both natural:

• Eu gosto de fazer exercício no parque.
• Eu gosto de me exercitar no parque.

Fazer exercício is often easier for learners and very widely used in everyday speech.

Yes. In Portuguese, the singular can be used for the general activity:

• fazer exercício = to exercise / to do exercise

You may also hear fazer exercícios, especially when talking about multiple exercises, routines, or specific practice activities.

Compare:

• fazer exercício = exercise in general
• fazer exercícios = do exercises / do workout movements / do practice exercises

In this sentence, the singular sounds completely natural.

No is a contraction of:

• em
  • o = no

So:

• no parque = in the park / at the park

This contraction is extremely common in Portuguese:

• na escola = in/at the school
• no Brasil = in Brazil
• nos Estados Unidos = in the United States

You usually cannot keep em o parque separate in normal Portuguese. It contracts to no parque.

Because parque here takes the definite article o.

So:

• em + o parque → no parque

In Portuguese, many places naturally use an article, especially when referring to a specific or familiar place in a general way, such as the park.

So no parque is the normal form here.

Usually it describes a habit or general preference.

• Quando faz sol in the present tense often means when/whenever it’s sunny
• eu gosto de fazer exercício no parque means this is something the speaker likes to do in that situation

So the full idea is something like:

• Whenever it’s sunny, I like to exercise in the park.

If you wanted one specific past occasion, you would normally use a different tense.

You could, but it is less common and less natural in everyday speech than quando faz sol.

• Quando faz sol = very common, everyday way to say when it’s sunny
• Quando está ensolarado = understandable, but more descriptive and less idiomatic in casual conversation

For a learner, quando faz sol is the best phrase to remember.

Because the sentence expresses a general preference, not a completed action.

• eu gosto de... = I like to...
• It describes what the speaker generally likes

The sentence is not saying the speaker is exercising right now. It says that in sunny weather, this is something they like doing.

Yes. Portuguese allows some flexibility.

For example:

• Quando faz sol, eu gosto de fazer exercício no parque.
• Eu gosto de fazer exercício no parque quando faz sol.

Both are correct. The first version emphasizes the condition first: when it’s sunny. The second starts with the speaker’s preference.

The original sentence sounds very natural and is a common way to structure this kind of idea.