Para mim, o silêncio da manhã ajuda a acalmar a mente.

Here Para mim means something like for me, to me, or in my experience.

It does not mean that something is physically being given to me. It sets the speaker’s personal point of view:

• Para mim, o silêncio da manhã ajuda... = For me / As far as I’m concerned, the morning silence helps...

It makes the sentence more personal. Without it, the sentence sounds more like a general statement.

Because para is a preposition, and after a preposition Portuguese normally uses the stressed object pronoun:

• para mim
• para ti
• para ele/ela

So:

• Para mim = correct

You use eu after para only when eu is the subject of an infinitive verb:

• Isto é para eu ler. = This is for me to read.

In your sentence, there is no infinitive verb with eu as its subject, so mim is the correct form.

The comma marks Para mim as an introductory or framing expression.

It is similar to English when you say:

• For me, ...
• Personally, ...

So the comma helps separate the speaker’s viewpoint from the main statement.

In very informal writing, some people might leave it out, but with this structure the comma is natural and standard.

Portuguese uses definite articles much more often than English does.

So where English might say:

• morning silence helps calm the mind

Portuguese very naturally says:

• o silêncio da manhã

The article o goes with silêncio, which is a masculine noun.

This does not necessarily mean one specific silence in a narrow sense; it can still sound general and natural.

Da manhã means of the morning or, more naturally in English, morning.

It is made from:

• de + a manhã = da manhã

So:

• o silêncio da manhã = the silence of the morning = the morning silence

This phrase modifies silêncio.

A useful contrast:

• da manhã describes the noun
  
  • o silêncio da manhã = the morning silence
• de manhã usually means in the morning
  
  • De manhã, leio. = In the morning, I read.

This is the verb pattern ajudar a + infinitive:

• ajudar a acalmar
• ajudar a compreender
• ajudar a dormir

So here it means:

• helps to calm

In European Portuguese, ajudar a + infinitive is especially common and natural.
You may also hear forms without a in other varieties, especially in Brazilian Portuguese, but in Portugal ajudar a acalmar is a very standard choice.

They are doing two different jobs:

1. ajuda a acalmar

   • this a is a preposition
   • it belongs to the structure ajudar a + infinitive

2. a mente

   • this a is the definite article
   • it means the
   • mente is a feminine noun, so it takes a

So:

• ajuda a acalmar a mente
• helps to calm the mind

Because Portuguese often leaves out the possessive when it is obvious or unnecessary.

Here, a mente sounds natural and slightly more general:

• a mente = the mind

Since Para mim already shows whose perspective we are talking about, adding minha is often unnecessary.

If you say:

• Para mim, o silêncio da manhã ajuda a acalmar a minha mente

that is also grammatical, but it sounds a bit more explicit and possibly more emphatic.

Yes.

If you say:

• O silêncio da manhã ajuda a acalmar a mente.

the sentence becomes more general, like a statement about what morning silence does.

If you say:

• Para mim, o silêncio da manhã ajuda a acalmar a mente.

it becomes more personal:

• For me / in my experience, morning silence helps calm the mind.

So Para mim is optional grammatically, but it changes the nuance.

Yes.

• o silêncio da manhã
• o silêncio matinal

Both are correct and mean roughly the same thing.

The difference is mostly style:

• o silêncio da manhã sounds very natural and everyday
• o silêncio matinal sounds a bit more literary or formal

A learner will probably hear da manhã more often in ordinary speech.

Manhã is one of the words learners often notice because of the nasal vowel.

A rough guide:

• manhã sounds approximately like ma-NYÃ
• the final ã is nasal, so the sound comes partly through the nose

A few pronunciation points:

• nh is like the ny sound in canyon
• ã is a nasal vowel, not a normal English a
• the stress is on the last syllable: ma-NHÃ

So the word is not pronounced like manha with a plain final vowel. The nasal sound is important.