A ferida no queixo já fechou, mas a testa ainda está um pouco inchada.

Portuguese uses definite articles much more often than English.

So:

• a ferida = the wound
• a testa = the forehead

Even when English might leave something more general, Portuguese often prefers the article when talking about a specific, known thing.

In this sentence, the speaker is talking about particular injuries, so a sounds completely natural.

No queixo means on the chin.

Here, no is a contraction:

• em = in / on / at
• o = the

So:

• em + o = no

Literally, a ferida no queixo is the wound on the chin.

This is a very common pattern in Portuguese:

• no braço = on the arm
• na mão = on the hand
• no rosto = on the face

Portuguese often uses the definite article with body parts instead of a possessive, especially when it is already obvious whose body part is being discussed.

So Portuguese commonly says:

• machuquei o braço = I hurt my arm
• a testa está inchada = the / her / his forehead is swollen, depending on context

In English, we usually say my chin, his forehead, etc. In Portuguese, that possessive is often unnecessary.

Já means already, and fechou is the preterite form of fechar.

So já fechou means:

• has already closed
• or more naturally in English here, has already healed over / closed up

With wounds, fechar can mean that the skin has closed.

Examples:

• O corte já fechou. = The cut has already closed up.
• A ferida já fechou. = The wound has already closed.

Both are possible, but they focus on slightly different things.

• já fechou emphasizes the completed event/process: the wound closed
• está fechada emphasizes the current state: the wound is closed

So:

• A ferida já fechou = The wound has already closed up.
• A ferida está fechada = The wound is closed.

The original sentence uses já fechou because it highlights that this part of the healing process has already happened.

Fechou is the pretérito perfeito of fechar.

Conjugation:

• eu fechei
• você/ele/ela fechou
• nós fechamos
• vocês/eles/elas fecharam

In this sentence, a ferida is the subject, so Portuguese uses fechou just like it would with ela fechou, because ferida is singular.

Mas means but.

It connects two contrasting ideas:

• A ferida no queixo já fechou = The wound on the chin has already closed
• mas a testa ainda está um pouco inchada = but the forehead is still a little swollen

So the contrast is:

• one injury has improved
• the other is still not fully better

Ainda here means still.

So:

• ainda está inchada = is still swollen

It shows that the condition continues up to the present moment.

Compare:

• já fechou = has already closed
• ainda está inchada = is still swollen

This pairing of já and ainda is very common in Portuguese because it clearly contrasts already and still.

Portuguese uses estar for temporary states and conditions, and ser for more permanent characteristics.

Swelling is a temporary physical condition, so:

• a testa está inchada = the forehead is swollen

Using é inchada would sound wrong here, because it would suggest a permanent or defining characteristic.

A useful rule:

• ser = what something is
• estar = how something is right now

Because inchada agrees with a testa, which is feminine singular.

• a testa → feminine singular
• adjective must match → inchada

Compare:

• o braço está inchado = the arm is swollen
• a mão está inchada = the hand is swollen

This kind of adjective agreement is very important in Portuguese.

Um pouco means a little or a bit.

So:

• um pouco inchada = a little swollen

It softens the description. The forehead is not described as extremely swollen, just somewhat swollen.

This placement is natural:

• está um pouco inchada

You will often see um pouco before an adjective:

• um pouco cansado = a little tired
• um pouco difícil = a little difficult
• um pouco preocupado = a little worried

Because the noun itself is already the subject:

• A ferida ... fechou
• a testa ... está inchada

Portuguese does not need to add ela here. In fact, repeating the pronoun would usually sound unnecessary unless you wanted extra emphasis.

So the normal pattern is simply:

• A ferida fechou
• A testa está inchada

Yes. Fechar can be transitive, but it can also be used in a way that means to close up on its own.

For example:

• Fechei a porta. = I closed the door.
  Here it is transitive.

But with things like wounds or openings:

• A ferida fechou. = The wound closed up.
• O buraco fechou. = The hole closed.

So this usage is normal and natural.

Yes. A few natural alternatives are:

• A ferida no queixo já sarou, mas a testa ainda está um pouco inchada.
• O machucado no queixo já fechou, mas a testa ainda está um pouco inchada.
• A ferida no queixo já está fechada, mas a testa ainda está um pouco inchada.

Some nuance differences:

• sarou focuses more on healed
• fechou focuses more on closed up
• está fechada focuses more on the current state

The original sentence is completely natural in Brazilian Portuguese.