Eu machuquei o tornozelo no parque, mas meu calcanhar está bem.

Yes, you often can leave out Eu in Brazilian Portuguese.

• Eu machuquei o tornozelo...
• Machuquei o tornozelo...

Both are natural, because the verb machuquei already shows that the subject is I.

Including Eu can add:

• emphasis
• contrast
• clarity

For example, Eu machuquei o tornozelo, mas ele machucou o joelho emphasizes that I hurt my ankle, while he hurt his knee.

Machuquei comes from the verb machucar, which means to hurt, to injure, or to get hurt/injured, depending on context.

In this sentence, machuquei o tornozelo means:

• I hurt my ankle
• I injured my ankle

It is very common in everyday Brazilian Portuguese for physical injury.

Examples:

• Machuquei a mão. = I hurt my hand.
• Ela machucou o joelho. = She hurt her knee.

Machuquei is the first-person singular preterite of machucar.

That means:

• machuquei = I hurt / I injured
• it refers to a completed action in the past

So the sentence suggests that the ankle injury happened at some specific time in the past.

Quick comparison:

• machuquei = I hurt / I injured
• machucava = I used to hurt / I was hurting
• tenho machucado = I have hurt / I have been hurting

In this sentence, the simple completed-past meaning is the best fit.

Portuguese often uses the definite article with body parts where English uses a possessive.

So Portuguese commonly says:

• machuquei o tornozelo
• literally: I hurt the ankle
• natural English: I hurt my ankle

This is very normal, especially when it is obvious whose body part it is.

More examples:

• Lavei as mãos. = I washed my hands.
• Ela quebrou o braço. = She broke her arm.
• Ele levantou a cabeça. = He raised his head.

Using meu tornozelo is possible, but it is usually less natural here unless you want emphasis or contrast.

Good question. Both are possible:

• mas o calcanhar está bem
• mas meu calcanhar está bem

Using meu makes the contrast a bit clearer and more explicit: my heel is fine.

So:

• o tornozelo is natural because it is the direct object of the verb and clearly belongs to the speaker
• meu calcanhar adds a little emphasis or specificity in the second clause

You may hear both patterns in real Brazilian Portuguese.

They are different parts of the foot/leg area:

• tornozelo = ankle
• calcanhar = heel

So the sentence contrasts two nearby body parts:

• the ankle got hurt
• the heel is fine

This kind of contrast is common with mas.

No is a contraction of:

• em + o = no

So:

• no parque = in the park / at the park

Portuguese very often contracts em with definite articles:

• em + o = no
• em + a = na
• em + os = nos
• em + as = nas

Examples:

• na escola = at school
• no carro = in the car
• nas férias = on vacation

So no parque is the normal form, not em o parque.

It can mean either, depending on context.

• in the park if you are thinking of being physically inside the park
• at the park if you are thinking more generally about the location

In many cases, English could use either one naturally.

So in this sentence:

• I hurt my ankle in the park
• I hurt my ankle at the park

Both are reasonable translations depending on the situation.

Mas means but, and it introduces a contrast.

Here the contrast is:

• one part is injured: machuquei o tornozelo
• another part is okay: meu calcanhar está bem

If you used e (and), the contrast would be weaker:

• Eu machuquei o tornozelo e meu calcanhar está bem.

That is grammatical, but mas sounds more logical and natural because the speaker is contrasting injury with no injury.

Because estar is used for a state or condition, while ser is used for more permanent identity or characteristics.

Here, meu calcanhar está bem means:

• my heel is fine
• my heel is okay

This is a temporary or current condition, so estar is the correct verb.

Examples:

• Estou bem. = I’m fine.
• Ela está cansada. = She is tired.
• O tornozelo está inchado. = The ankle is swollen.

Using ser here would sound wrong.

Here bem means well, fine, or okay.

So está bem means:

• is fine
• is okay
• is doing well

In this sentence, it means the heel is not injured or not causing problems.

Other uses of bem:

• Estou bem. = I’m fine.
• Ele canta bem. = He sings well.
• Muito bem! = Very good!

So bem is a very flexible word.

It can be reflexive, but it does not have to be.

Two common patterns are:

1. Machuquei o tornozelo.
   = I hurt my ankle.

2. Me machuquei.
   = I got hurt / I hurt myself.

If you specify the body part directly, machuquei o tornozelo is completely natural.

If you want the more general idea of injuring yourself, you can say:

• Eu me machuquei no parque. = I got hurt in the park.

You can even combine them:

• Eu machuquei o tornozelo no parque.
• Eu me machuquei no parque e torci o tornozelo.

So the sentence as given is perfectly normal.

In Brazilian Portuguese, machuquei is pronounced approximately like:

• ma-shoo-KAY

A few details:

• ch sounds like English sh
• quei sounds roughly like kay
• the stress falls on the last syllable: -quei

So:

• ma-chu-QUEI
• more naturally: ma-shoo-KAY

This is only an approximation, but it helps an English speaker get close.

You could, but it is less common in everyday speech for this context.

• machucar is very common and conversational for to hurt/injure
• ferir often sounds a bit more formal, serious, or literary, depending on context

So:

• Machuquei o tornozelo = very natural in daily speech
• Feri o tornozelo = understandable, but less likely in ordinary conversation

For a learner, machucar is usually the safer everyday choice.

Yes, to some extent.

The original sentence:

• Eu machuquei o tornozelo no parque, mas meu calcanhar está bem.

Some natural variations:

• Machuquei o tornozelo no parque, mas meu calcanhar está bem.
• No parque, eu machuquei o tornozelo, mas meu calcanhar está bem.
• Eu machuquei o tornozelo, mas meu calcanhar está bem.
  (if the location is omitted)

Changing the order can shift emphasis:

• No parque... emphasizes where
• Eu... emphasizes who
• leaving out Eu sounds more neutral and natural in many cases

The original word order is very normal.

Yes, it is natural and understandable.

It uses:

• a very common past tense form (machuquei)
• normal location structure (no parque)
• a natural contrast with mas
• a common expression of condition (está bem)

A Brazilian speaker might also say slight variations such as:

• Machuquei o tornozelo no parque, mas o calcanhar está bem.
• Eu machuquei o tornozelo no parque, mas meu calcanhar não foi afetado.
  (more formal or specific)

But the original sentence sounds perfectly fine.