A guia conhece bem o centro e sempre mostra uma paisagem bonita para a gente.

Because guia here refers to a female guide, so the article is feminine: a guia.

A few useful notes:

• o guia = a male guide
• a guia = a female guide

Also, guia can sometimes mean guidebook or manual, and in that case it is often masculine: o guia turístico.

So in this sentence, a guia tells you the person is a woman.

Portuguese often leaves out the subject pronoun when it is clear from context. This is very normal.

So instead of saying:

• Ela conhece bem o centro...

Portuguese can simply say:

• Conhece bem o centro...

In your sentence, the noun a guia is already there, so adding ela would be unnecessary.

Because conhecer and saber are not used the same way.

• conhecer = to know a place, person, or thing through familiarity/experience
• saber = to know a fact, know information, or know how to do something

So:

• A guia conhece bem o centro = The guide knows the downtown area well / is very familiar with it

You would not normally use saber here, because she is familiar with the place, not just aware of a fact about it.

Bem means well here. It modifies the verb conhece.

So:

• conhece bem = knows well / is very familiar with

This is a very common pattern in Portuguese:

• fala bem português = speaks Portuguese well
• cozinha bem = cooks well
• conhece bem a cidade = knows the city well

O centro usually means the city center, downtown, or the central area of a town or city.

In Brazilian Portuguese, this is a very common way to refer to downtown:

• Vou ao centro. = I’m going downtown.
• O centro está cheio hoje. = Downtown is crowded today.

So in this sentence, o centro most likely means the central area of the city the guide knows well.

Yes, both are possible.

• sempre mostra
• mostra sempre

Both mean always shows. The position of sempre is somewhat flexible in Portuguese.

In your sentence, sempre mostra sounds very natural and neutral.
Mostra sempre is also natural, but it can sound slightly more emphatic depending on context.

Because uma means a / one, so it introduces something non-specific:

• uma paisagem bonita = a beautiful landscape/view

If you said a paisagem bonita, it would usually mean the beautiful landscape, referring to a specific one already known in the conversation.

So uma makes the idea more general: she always shows us some beautiful view.

In Portuguese, adjectives often come after the noun.

So:

• paisagem bonita = beautiful landscape/view

This is the most normal order.
Putting the adjective before the noun is sometimes possible, but it often sounds more literary, emotional, or stylistically marked:

• bonita paisagem

That is not the usual everyday choice here.

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

Here:

• paisagem is feminine
• so the adjective must also be feminine: bonita

Compare:

• um lugar bonito = a beautiful place
• uma paisagem bonita = a beautiful landscape
• paisagens bonitas = beautiful landscapes

Here, para a gente means for us or to us.

In Brazilian Portuguese, a gente is very commonly used in everyday speech to mean we/us, even though literally it originally means the people or people.

So:

• mostra uma paisagem bonita para a gente = shows a beautiful view to us / for us

This is very natural in Brazil.

Grammatically, a gente is treated as singular, but in meaning it often refers to we/us.

That means:

• a gente vai = we go
• a gente gosta = we like

Notice the verb is singular:

• vai, not vamos
• gosta, not gostamos

In your sentence, para a gente means to us/for us, even though the expression itself is grammatically singular.

Yes. You could say:

• A guia conhece bem o centro e sempre mostra uma paisagem bonita para nós.

This is correct, but it sounds a bit more formal or careful.

In Brazilian Portuguese:

• para a gente = very common, natural, conversational
• para nós = correct, but often more formal or less conversational

So the version in your sentence sounds very natural for spoken Brazilian Portuguese.

Yes. A more compact version would be:

• A guia conhece bem o centro e sempre nos mostra uma paisagem bonita.

This also means The guide knows downtown well and always shows us a beautiful view.

A quick comparison:

• mostra uma paisagem bonita para a gente = very common, clear, conversational
• nos mostra uma paisagem bonita = also correct, a little more compact, sometimes a bit more written or formal depending on context

In modern Brazilian Portuguese, many speakers prefer the para a gente type structure in everyday speech.

Mostrar means to show and here it has:

• a direct object: uma paisagem bonita
• an indirect object: para a gente

So the structure is:

• mostrar algo para alguém
• to show something to someone

Examples:

• Ela mostra o mapa para os turistas. = She shows the map to the tourists.
• O professor mostra um vídeo para a turma. = The teacher shows a video to the class.

Your sentence follows exactly this pattern.