Na aula, a professora sugeriu um livro novo de português.

Because na is the normal contraction of em + a.

• em = in, on, at
• a = the, feminine singular

So:

• em + a = na

This is very common in Portuguese:

• no = em + o
• na = em + a
• nos = em + os
• nas = em + as

So na aula literally means in the lesson / in class, and often more naturally during class.

Usually it means during the lesson / in class, not necessarily physically inside the classroom.

So in this sentence, Na aula, a professora sugeriu... most naturally means:

• During class, the teacher suggested...

If you specifically wanted to talk about physical location, Portuguese can still use na aula, but context usually makes it clear. Here it sounds more like a time/context expression than a location.

Because Na aula is an introductory phrase placed at the beginning of the sentence.

It sets the scene first:

• Na aula, a professora sugeriu um livro novo de português.

In English, this is similar to:

• In class, the teacher suggested...

The comma helps separate that opening context from the main clause. In short sentences, Portuguese can sometimes omit this comma, but here it is very natural and clear.

Portuguese often uses the definite article much more than English does.

So where English often says:

• the teacher suggested...
  or even just
• teacher suggested... in some special contexts

Portuguese normally says:

• a professora sugeriu...

Here a professora means the teacher, referring to a specific teacher already known in the context.

Using no article here would sound unnatural in normal Portuguese.

Because professora is feminine, and professor is masculine.

• o professor = the male teacher
• a professora = the female teacher

So this sentence tells you that the teacher is a woman.

Sugeriu is the pretérito perfeito in Portuguese, which usually corresponds to the simple past in English.

It is:

• 3rd person singular
• from the verb sugerir = to suggest

So:

• eu sugeri = I suggested
• tu sugeriste
• ele/ela sugeriu = he/she suggested

In this sentence, a professora sugeriu means the teacher suggested.

It describes a completed action in the past.

Because sugerir can take a direct object directly.

So Portuguese says:

• sugerir um livro = to suggest a book

You do not need a preposition before um livro.

If you want to mention the person receiving the suggestion, Portuguese can use a:

• A professora sugeriu um livro aos alunos.
  = The teacher suggested a book to the students.

So in your sentence:

• um livro novo de português is the thing being suggested

Both are possible, but the most neutral meaning here is um livro novo.

With adjectives in Portuguese, position can matter:

• um livro novo = a book that is new
• um novo livro = a new book, often with a slightly more subjective idea like another/newly introduced book

In many situations the difference is small, but:

• noun + adjective is often the more neutral, descriptive order
• adjective + noun can sound a bit more literary, emphatic, or interpretive

So um livro novo is the straightforward way to say a new book.

Because adjectives in Portuguese usually agree with the noun they describe.

Here the noun is:

• livro = masculine singular

So the adjective must also be masculine singular:

• novo

Compare:

• um livro novo = a new book
• uma revista nova = a new magazine

The adjective changes form to match gender and number.

Here de português most naturally means something like:

• for Portuguese class
• about the Portuguese language
• a Portuguese textbook / Portuguese book, depending on context

So um livro novo de português is not usually understood as just any book written in Portuguese. It more often means a book related to the subject Portuguese.

In school contexts, livro de português often means a Portuguese-language textbook or class book.

Because in Portuguese, names of languages are normally written in lowercase.

So Portuguese writes:

• português
• inglês
• francês

English is different, because English capitalizes language names:

• Portuguese
• English
• French

So de português is correct in Portuguese spelling.

Yes. Portuguese word order is fairly flexible, especially with introductory phrases.

For example, these are all possible:

• Na aula, a professora sugeriu um livro novo de português.
• A professora sugeriu um livro novo de português na aula.
• A professora, na aula, sugeriu um livro novo de português.

But they do not all sound equally natural in every context.

The original version is very natural because it starts with the setting:

• Na aula... = during class...

That helps frame the sentence before giving the main action.

It works in both European Portuguese and Brazilian Portuguese.

The grammar and vocabulary are standard in both varieties:

• Na aula
• a professora
• sugeriu
• um livro novo de português

The main differences would be pronunciation and possibly how often certain word orders are preferred in speech, but the sentence itself is perfectly natural in both. The lowercase português is also normal in standard Portuguese spelling.