Setembro é o mês em que minha filha apresenta o trabalho final da escola.

In Portuguese, month names usually appear without an article when you are simply naming the month.

So Setembro é o mês... is natural and standard.

Examples:

• Janeiro é quente aqui.
• Outubro é um mês movimentado.

Also, unlike English, month names are normally not capitalized in Portuguese unless they begin a sentence. So in the middle of a sentence, you would usually write setembro, not September-style Setembro.

Em que means in which here.

The structure is:

• o mês = the month
• em que = in which

So literally:

• Setembro é o mês em que...
• September is the month in which...

This is a very common way to connect a noun to a clause that gives more information about it.

Other examples:

• A cidade em que moro = the city where I live
• O dia em que cheguei = the day when/on which I arrived

Usually, in this sentence, em que is the best choice.

• Setembro é o mês em que minha filha apresenta... = natural and standard

Using quando after o mês is generally not the normal standard structure:

• o mês quando... sounds off to many speakers

A more natural alternative would be to change the sentence structure, for example:

• Setembro é quando minha filha apresenta o trabalho final da escola.
• Em setembro, minha filha apresenta o trabalho final da escola.

So yes, quando can appear in a different version of the sentence, but it does not neatly replace em que after o mês.

In Brazilian Portuguese, possessives like meu, minha, seu, nossa can appear with or without a definite article.

So both are possible:

• minha filha
• a minha filha

In Brazil, article use before possessives varies by region, style, and level of formality. In this sentence, minha filha without the article sounds completely natural.

Very roughly:

• minha filha = slightly leaner, very common
• a minha filha = also common, sometimes a little more marked or regional

Yes, but Portuguese often uses the simple present for scheduled or expected future events, especially when the time is clear from context.

Here, Setembro already places the action in time, so apresenta can naturally mean:

• is presenting
• presents
• will present

This is similar to English sentences like:

• My daughter presents her final project in September
• The train leaves tomorrow

If you wanted to make the future more explicit, you could say:

• minha filha vai apresentar o trabalho final da escola

But the original sentence is perfectly natural.

Here apresentar most likely means to present in the sense of giving a presentation, showing, or formally presenting a project or piece of work.

So apresenta o trabalho final suggests that the daughter is:

• presenting her final project
• giving a final presentation
• formally showing her final school work

It does not usually mean simply handing it in. If the idea were submitting it, Portuguese would more likely use verbs such as:

• entregar
• enviar
• submeter (more formal/academic)

Not usually.

Trabalho final normally means a final project, final paper, or final assignment. It is some piece of work the student prepares and then possibly presents.

A final exam would more likely be:

• prova final
• exame final

So trabalho final points to an assignment or project, not a test.

Because da escola is linked to o trabalho final, not to the verb apresenta.

• o trabalho final da escola = the school’s final project / the final school project
• na escola = at school

So the original means the project belongs to the school context. It describes what kind of project it is.

Compare:

• minha filha apresenta o trabalho final da escola
  = she presents the final school project

• minha filha apresenta o trabalho final na escola
  = she presents the final project at school

Those are different meanings.

O is used because the sentence refers to a specific final project, presumably one that is known from context.

• o trabalho final = the final project
• um trabalho final = a final project

Using um would sound less specific, as if it were just one among many possible final projects. In normal school context, there is usually a specific final assignment, so o trabalho final makes sense.

Yes, absolutely. That version is very natural.

Compare:

• Setembro é o mês em que minha filha apresenta o trabalho final da escola.
• Em setembro, minha filha apresenta o trabalho final da escola.

The difference is mainly in focus:

• Setembro é o mês em que... emphasizes September as the month
• Em setembro... is more direct and straightforward: In September...

Both are correct, but the original has a slightly more descriptive or explanatory tone.

Yes, basically.

You could say:

• Setembro é o mês em que minha filha apresenta...
• Setembro é o mês no qual minha filha apresenta...

Both are grammatically correct and mean the same thing. But there is a style difference:

• em que = more common, lighter, more natural in everyday speech
• no qual = more formal, heavier, more written

So most speakers would prefer em que in ordinary conversation.