Talvez o goleiro defenda outro pênalti.

Because talvez usually introduces uncertainty, and in standard Portuguese that normally calls for the subjunctive.

So:

• ele defende = indicative, more like a plain statement of fact
• ele defenda = subjunctive, used here because the action is only a possibility

That is why Talvez o goleiro defenda outro pênalti is the standard form.

It is the present subjunctive.

Even though it is called present subjunctive, in a sentence like this it often refers to a future possibility:

• Talvez o goleiro defenda outro pênalti = maybe the goalkeeper will save another penalty

So the form is grammatically present subjunctive, but the meaning can point to something that may happen later.

Defender is an -ER verb.

A common way to form the present subjunctive is:

1. Start with the eu form of the present indicative: eu defendo
2. Remove the final -o
3. Add the subjunctive endings for -ER/-IR verbs

That gives:

• eu defenda
• você/ele/ela defenda
• nós defendamos
• vocês/eles/elas defendam

So in this sentence, o goleiro defenda means the goalkeeper may save.

In standard Portuguese, talvez is usually followed by the subjunctive when it means maybe / perhaps in the sense of uncertainty:

• Talvez ele venha
• Talvez chova
• Talvez o goleiro defenda outro pênalti

In casual speech, some Brazilians do sometimes use the indicative after talvez, but that is not the form learners should aim for at first. The safest and most standard choice is:

• talvez + subjunctive

Because talvez can directly introduce the clause by itself.

So Portuguese says:

• Talvez o goleiro defenda outro pênalti

not normally:

• Talvez que o goleiro defenda outro pênalti

For a learner, the simplest rule is: after talvez, just put the clause directly, usually with the subjunctive.

O goleiro means the goalkeeper.

Portuguese often uses the definite article when talking about a specific person or role that is known from the context. So this sentence sounds like it is referring to a particular goalkeeper, not just any goalkeeper in general.

Compare:

• o goleiro = the goalkeeper, a specific one
• um goleiro = a goalkeeper, any one goalkeeper

Here, o goleiro suggests that the speaker has a particular goalkeeper in mind.

Because outro often works like a determiner by itself, so Portuguese normally says:

• outro pênalti = another penalty

You do not need um before it.

You may sometimes hear um outro pênalti, but that usually adds a slight nuance, such as emphasis or contrast. For most learners, the basic and most neutral form is:

• outro pênalti

Because outro usually comes before the noun it modifies:

• outro jogo
• outra chance
• outro pênalti

So this word order is the normal one. It works much like another in English, which also comes before the noun.

In football/soccer, defender um pênalti means to save a penalty.

So the goalkeeper is not defending a penalty in the literal English sense. In sports Portuguese, this expression means the goalkeeper stops the shot.

Very common examples:

• O goleiro defendeu o pênalti = The goalkeeper saved the penalty.
• Ele pegou o pênalti = He saved the penalty.
  (This is also very common in Brazilian Portuguese.)

In everyday Brazilian Portuguese, pênalti can refer to the whole penalty situation, but in a sentence like defender um pênalti, it clearly means the penalty kick being taken and saved by the goalkeeper.

So here the meaning is:

• the goalkeeper may save another penalty kick

The word is pronounced roughly like PEN-aw-tchee in Brazilian Portuguese, though exact pronunciation depends on accent.

The circumflex in pê shows the stressed syllable and the vowel quality. The stress is on the first syllable:

• PÊ-nal-ti

This word is a borrowing related to English penalty, but Portuguese adapted the spelling and pronunciation.

Yes. That is also possible.

Compare:

• Talvez o goleiro defenda outro pênalti
• O goleiro talvez defenda outro pênalti

Both are natural. The difference is mostly one of rhythm or emphasis:

• starting with talvez highlights the uncertainty right away
• putting o goleiro first puts the goalkeeper slightly more in focus

Both are good Portuguese.

Yes, goleiro is the normal Brazilian Portuguese word for goalkeeper.

In European Portuguese, the usual term is guarda-redes.

So for Brazilian Portuguese, o goleiro is exactly the right choice.