Learn Hardcore Portuguese (Brazil): Geralmente o jornal publicará um artigo sobre o mesmo assunto, com a opinião de vários leitores. - Generally the newspaper will publish an article about the same topic, with the opinion of several readers.

Putting geralmente (generally / usually) at the beginning is very common in Portuguese to set the overall context of the sentence, a bit like English: “Usually, the newspaper will publish…”

If you move geralmente after the subject (O jornal geralmente publicará…), it sounds slightly more neutral and less “framing” or emphatic, but it is also completely correct.

You would normally avoid O jornal publicará geralmente um artigo… – that position for geralmente is possible but less natural here.

Why is the future tense publicará used with Geralmente? Would O jornal geralmente publica… be more natural?

In everyday Brazilian Portuguese, for a habitual action, present tense is more natural:

Geralmente o jornal publica um artigo…
(The newspaper usually publishes an article…)

Using publicará (simple future) suggests either:

A formal / written style (e.g. instructions, descriptions of procedures), or
A future-looking context: talking about what the newspaper will usually do in a certain future situation.

If the intended meaning is a general habit in the present, publica is the default in Brazil.
If the meaning is “In that situation, the newspaper will generally publish…”, publicará works fine, especially in written or more formal language.

Colloquially, Brazilians also use the periphrastic future:

Geralmente o jornal vai publicar um artigo…
(less formal than publicará, still future).

What is the difference between o jornal and um jornal here?

o jornal = the newspaper (a specific one, known from context)
um jornal = a newspaper (any newspaper, non-specific)

In the sentence, o jornal suggests we are talking about a particular newspaper (for example, the local newspaper or a specific publication already mentioned).

Using um jornal publicará… would sound like “some newspaper or other will publish…”, not a specific one the speaker has in mind.

Why do we need the article o in o jornal? Could we just say Geralmente jornal publicará…?

No. In Portuguese, singular countable nouns almost always require an article (or another determiner like este, meu, etc.), unless they are in a few special patterns (titles, lists, etc.).

So you need:

o jornal (the newspaper)
um jornal (a newspaper)

Just jornal on its own here would be ungrammatical. English allows “Newspaper will publish…” in headlines; Portuguese does not normally allow that in full sentences.

What does sobre mean in um artigo sobre o mesmo assunto? Is it like about or on?

Yes, sobre here means about / on (the topic of):

um artigo sobre política – an article about politics
um livro sobre música – a book on music

It is the standard preposition to introduce the subject matter of a text, talk, documentary, etc.

You would not normally use em or de in this context. Um artigo em política or um artigo de política would sound wrong or at least very odd.

What exactly does o mesmo assunto mean, and what are other uses of mesmo?

o mesmo assunto = the same subject / the same topic.

Here mesmo works as an adjective meaning same and it agrees in gender and number with the noun:

o mesmo assunto – the same subject (masculine singular)
a mesma ideia – the same idea (feminine singular)
os mesmos assuntos – the same subjects (masculine plural)

Other common uses of mesmo:

Emphatic / intensifying:
- Ele mesmo fez isso. – He himself did that.
- Na mesma hora. – At that very time.
“Even” / “actually” in some expressions:
- Eu gostei mesmo. – I really did like it.

Why is it o mesmo assunto and not a mesma assunto?

Because assunto is a masculine noun in Portuguese:

o assunto – the subject / matter / issue

Adjectives, articles, and words like mesmo must agree in gender and number:

o mesmo assunto (masc. sing.)
a mesma questão (fem. sing.)
os mesmos assuntos (masc. pl.)
as mesmas questões (fem. pl.)

So a mesma assunto would be incorrect gender agreement.

Why is there a comma before com a opinião de vários leitores? Could we omit it?

The comma marks com a opinião de vários leitores as an additional piece of information, almost like an aside:

Geralmente o jornal publicará um artigo sobre o mesmo assunto, com a opinião de vários leitores.

This sounds like:
“The newspaper will usually publish an article on the same subject, with the opinions of several readers.”

Without the comma:

Geralmente o jornal publicará um artigo sobre o mesmo assunto com a opinião de vários leitores.

it can sound a bit more “integrated” or heavy, as if the opinião de vários leitores is a tightly bound complement of assunto. The comma is natural and preferred in writing because this final phrase is more like an extra detail about how the article is presented.

Grammatically, it can work either way, but the comma makes the sentence easier to parse and more natural in standard written Portuguese.

Why is it opinião de vários leitores and not opinião por vários leitores?

In Portuguese, de is typically used to express possession, origin, or authorship:

a opinião de vários leitores – the opinion of several readers
um livro de Machado de Assis – a book by Machado de Assis

por is used for agents mainly with passive constructions:

O artigo foi escrito por vários leitores. – The article was written by several readers.

Here we are not describing a passive action but whose opinion it is, so de is the natural preposition: the opinion of several readers.

What is the nuance of vários leitores compared to muitos leitores or alguns leitores?

vários leitores – several readers / quite a few readers
- Suggests more than just a couple, but not necessarily a very large number.
muitos leitores – many readers
- Emphasizes a large quantity.
alguns leitores – some readers / a few readers
- Suggests a small, non-specific number.

So a opinião de vários leitores suggests a reasonably diverse set of readers, but it does not necessarily mean a huge number.

Why is opinião singular (a opinião de vários leitores) and not as opiniões de vários leitores?

Both are possible, but they emphasize slightly different things:

a opinião de vários leitores
- Focus on a sort of collective opinion or the general viewpoint formed from several readers.
as opiniões de vários leitores
- Focus on multiple individual opinions (different opinions) from several readers.

In practice, context decides which sounds better. The singular can work as “the general opinion” coming from a group, which is likely the idea here.

Could the word order be O jornal publicará geralmente um artigo…? Is that correct?

It is grammatically possible, but it is less natural in this sentence. Typical placements for geralmente are:

Geralmente o jornal publicará um artigo…
O jornal geralmente publicará um artigo…

Placing geralmente between the verb and the object (publicará geralmente um artigo) is not wrong, but it tends to sound more marked or awkward in everyday speech. Native speakers usually put geralmente near the beginning of the clause or right after the subject.

Is there any difference in meaning or style between publicará and vai publicar here?

Yes, in Brazilian Portuguese:

publicará
- Simple (synthetic) future, more formal / written or neutral.
- Common in news, official texts, instructions.
vai publicar
- Periphrastic future, very common in spoken and informal language.
- Feels more conversational.

Meaning-wise, both indicate future. If this sentence appears in a newspaper-style or textbook-like context, publicará fits well. In everyday speech, many Brazilians would naturally say:

Geralmente o jornal vai publicar um artigo…