Ell està en contra de la banca en línia.

Yes. Catalan often drops subject pronouns when the verb already makes the subject clear.

So Ell està en contra de la banca en línia can also be:

Està en contra de la banca en línia.

Both are correct. Adding ell makes the subject more explicit, and it can add emphasis or contrast, for example if you are comparing him with someone else:

Ella hi està a favor, però ell està en contra.
He is in favor, but he is against it.

So ell is not always necessary, but it is perfectly natural when you want to stress he.

Catalan uses estar en contra de for the idea to be against something.

So the normal expression is:

estar en contra de + noun / idea

Examples:

• Està en contra del projecte.
• Estem en contra d’aquesta proposta.

You should learn en contra de as a fixed expression that goes with estar.

En contra de means against.

It is a set phrase, and it is followed by de:

• en contra de la banca en línia
• en contra del canvi
• en contra d’aquesta idea

Notice that the de changes form depending on what follows:

• de + el = del
• de + els = dels
• before a vowel, you often get d’

Examples:

• en contra del banc
• en contra dels canvis
• en contra d’internet

So in your sentence, en contra de la banca en línia is completely regular because la banca is feminine singular.

These two words are related, but they do not mean exactly the same thing.

• el banc = the bank as an institution, company, or building
• la banca = banking or the banking sector / system

So:

• el banc might refer to a specific bank
• la banca en línia means online banking as a service or system

That is why la banca en línia is the natural phrase here.

Yes. En línia is the standard Catalan equivalent of online, and it is normally written as two words.

Examples:

• compres en línia = online shopping
• classes en línia = online classes
• banca en línia = online banking

Catalan usually prefers this structure rather than borrowing the English word directly in standard usage.

Usually it stays right after the noun it describes:

la banca en línia

That is the most natural position because it clearly modifies banca.

A different order would usually sound less natural or would change the rhythm of the sentence. So for learners, the best rule is:

noun + en línia

Examples:

• curs en línia
• pagament en línia
• servei en línia

Yes, there are a few natural alternatives, depending on style and nuance.

Common alternatives:

• Ell s’oposa a la banca en línia. = He opposes online banking.
• Ell no està a favor de la banca en línia. = He is not in favor of online banking.

But està en contra de is very direct and very common, so it is an excellent phrase to learn.

In this sentence, yes, the article is natural and expected.

Catalan often uses definite articles with general concepts more than English does. English says online banking, with no article, but Catalan naturally says:

la banca en línia

This is very common in Catalan:

• la música
• la història
• la tecnologia
• la banca en línia

So even if English has no the, Catalan may still use el / la / els / les.

The written accent in línia shows the stress pattern.

It is stressed on the first syllable: LÍ-ni-a.

The accent mark helps show that the stress does not fall where you might otherwise expect it. This is useful because stress is important in Catalan pronunciation.

So:

• línia = stress on lí

If you are reading it aloud, try: en LÍ-ni-a

Yes. It is grammatical, natural, and easy to understand.

A native speaker might omit ell unless they want emphasis, so in many contexts you would also hear:

Està en contra de la banca en línia.

But the full version with ell is still perfectly normal, especially in teaching examples or when contrasting different people’s opinions.