A torcida canta na arquibancada.

Because torcida is a collective noun. It is grammatically singular, even though it refers to many supporters as a group.

So in Portuguese, it normally takes a singular verb:

• A torcida canta. = the crowd/supporters sing
• not usually A torcida cantam.

This is similar to English words like the team or the crowd, which can refer to many people but are often treated as one unit.

Torcida usually means the supporters, the fan base, or the crowd cheering for a team, especially in sports.

It is different from:

• torcedor / torcedora = one fan, one supporter
• torcedores / torcedoras = fans, supporters
• fãs = fans in a more general sense

So:

• A torcida = the supporters as a collective group
• Os torcedores = the individual supporters

In a stadium context, torcida is very common and natural.

Portuguese uses definite articles much more often than English.

So a torcida is the normal way to say the crowd / the supporters in a general, known context.

If you remove the article and say just torcida, it usually sounds less natural in a full sentence like this, unless it is part of a headline, label, or a more special structure.

For everyday speech, A torcida canta is the standard form.

Because the subject is a torcida, which is singular.

• A torcida canta. = singular subject + singular verb
• Os torcedores cantam. = plural subject + plural verb

Compare:

• A torcida canta na arquibancada.
• Os torcedores cantam na arquibancada.

Both can refer to many people in real life, but the grammar changes depending on whether the noun is singular or plural.

Na is a contraction of:

• em
  • a = na

So:

• na arquibancada = in the stands / on the bleachers

This happens very often in Portuguese:

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

Examples:

• no estádio = in the stadium
• na arquibancada = in the stands
• nas cadeiras = in the seats

Arquibancada refers to the stands, bleachers, or seating area where spectators sit or stand in a stadium or sports venue.

Depending on context, English might translate it as:

• the stands
• the bleachers
• the terraces (in some varieties of English)
• the grandstand (sometimes, depending on the venue)

In Brazilian sports language, arquibancada is a very common word.

Literally, canta means sings. But in a soccer or stadium context, it can also naturally suggest chanting or singing supporter songs.

So depending on the translation, English might use:

• The crowd sings in the stands.
• The supporters chant in the stands.

The Portuguese word is still cantar, but the exact English choice depends on the context.

Yes. That is also correct, but the meaning is a little different.

• A torcida canta na arquibancada.
  Can mean a general fact, a vivid description, or something that happens there.

• A torcida está cantando na arquibancada.
  Emphasizes that the action is happening right now.

In Brazilian Portuguese, both forms are common, but estar + gerund is especially common for actions in progress.

Because torcida is a feminine noun, so it takes the article a:

• a torcida

This grammatical gender does not mean the crowd is female. It is just the gender of the noun.

Portuguese nouns have grammatical gender, and adjectives/articles must agree with the noun:

• a torcida animada
• a torcida brasileira

Even if the supporters are mixed or mostly male, the noun torcida stays feminine.

Yes. Portuguese allows some flexibility in word order.

For example:

• A torcida canta na arquibancada.
• Na arquibancada, a torcida canta.

Both are correct. The second version puts more emphasis on where the action happens.

The most neutral order is usually:

• subject + verb + place

So the original sentence sounds very natural.

A helpful approximation is:

ar-kee-ban-CA-da

A few pronunciation notes:

• qui in arqui- sounds like kee
• the stressed syllable is can: ar-qui-ban-CA-da
• the final da is light, not strongly stressed

And for the whole sentence, a rough pronunciation guide is:

a tor-SEE-da CAN-ta na ar-kee-ban-CA-da

This is only an approximation, but it can help an English speaker get started.