A comissão bancária aparece no extrato bancário.

Because comissão is a feminine singular noun, and here it is being used with the definite article a, meaning the.

• a comissão = the fee / the commission
• comissão by itself = fee / commission in a more general sense

In Portuguese, articles are used more often than in English, so A comissão bancária sounds natural where English might simply say Bank charges appear... or The bank fee appears...

In this sentence, comissão bancária usually means a bank fee, bank charge, or bank commission.

Although comissão can translate as commission, in financial contexts it often refers to a charge that the bank applies. So a learner should be careful not to think only of sales commission.

Common idea here:

• comissão bancária = a fee charged by the bank

Because adjectives in Portuguese usually agree with the noun in gender and number.

• comissão is feminine singular
• so the adjective must also be feminine singular: bancária

Compare:

• a comissão bancária = feminine singular
• o extrato bancário = masculine singular

So:

• bancária matches comissão
• bancário matches extrato

Portuguese often uses adjectives this way to make the meaning more specific.

Here:

• comissão bancária = bank fee / banking charge
• extrato bancário = bank statement

Even though both use a form of bancário, they describe different nouns:

• the fee is banking-related
• the statement is also banking-related

This repetition sounds normal and natural in Portuguese.

Aparece is the 3rd person singular of the present tense of the verb aparecer.

• aparecer = to appear / to show up
• aparece = appears / shows up

It matches a comissão bancária, which is singular.

Examples:

• A comissão aparece no extrato. = The fee appears on the statement.
• As comissões aparecem no extrato. = The fees appear on the statement.

Because aparecer focuses on something showing up, being listed, or appearing visibly on a statement.

So:

• aparece no extrato bancário = appears on the bank statement / shows up on the bank statement

If you used estar or ser, the meaning would be different:

• está no extrato = it is on the statement
• aparece no extrato = it appears / shows up on the statement

In this context, aparecer is very natural because bank statements display or list items.

Because no is the contraction of em + o.

• em = in / on
• o = the
• em + o = no

So:

• no extrato bancário = on the bank statement

This kind of contraction is very common in Portuguese:

• em + a = na
• em + os = nos
• em + as = nas

Examples:

• na conta = in the account
• nos documentos = in the documents

Portuguese often uses em where English uses either in or on, depending on context.

So:

• no extrato bancário literally looks like in the bank statement
• but the natural English translation is on the bank statement

This is normal. Portuguese does not always divide in and on the same way English does.

Yes, but the original order is the most neutral and natural.

Standard order:

• A comissão bancária aparece no extrato bancário.

You could also say:

• No extrato bancário aparece a comissão bancária.

This puts more emphasis on where it appears. It is grammatical, but less neutral.

For learners, the original sentence is the best model:

• subject + verb + prepositional phrase

A few useful ones:

• comissão
  The stress is on the last syllable: co-mi-SSÃO
  The ão sound is nasal, which is important in Portuguese.

• bancária
  The stress is on cá: ban-CÁ-ri-a

• aparece
  Usually pronounced with stress on re: apa-RE-ce

• extrato
  Stress on tra: ex-TRA-to

Also notice the written accents:

• comissão
• bancária

These help show stress and, in ão, also signal a characteristic Portuguese vowel sound.

Sometimes yes, but they are not always exactly the same.

• comissão bancária often refers to a bank charge/fee in a fairly broad banking sense
• taxa bancária can also mean bank fee, but taxa can suggest a charge, rate, or fee depending on context

So in real life, the exact term may depend on the bank and the type of charge. In this sentence, comissão bancária is perfectly natural and specific.

It is used in European Portuguese, and it is also understood in Brazilian Portuguese. It is the normal term for bank statement.

One spelling note:

• modern spelling is extrato
• you may sometimes see older European spelling extracto in older materials

For current standard Portuguese, extrato bancário is the form to learn.