A professora vai dar aula de português amanhã.

A is the definite article, meaning the. In Portuguese, it is very common to use the article before a noun like professora when talking about a specific person.

So A professora = the teacher.

If you said just professora by itself, that would usually only happen in special contexts, like calling out to her directly or using a headline-style phrase.

Because professora is the feminine form and professor is the masculine form.

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

Portuguese nouns referring to people often change form depending on gender.

Vai dar is a very common future construction in Brazilian Portuguese:

• ir in the present tense + infinitive

Here:

• vai = goes / is going to
• dar = to give

So vai dar aula literally looks like is going to give class, but naturally it means is going to teach or will teach.

Brazilian Portuguese often prefers ir + infinitive in everyday speech.

So instead of:

• A professora dará aula de português amanhã

people very often say:

• A professora vai dar aula de português amanhã

Both are correct, but vai dar sounds more natural and common in conversation.

Yes, literally it does. But as a set expression, dar aula means to teach or to give a class/lesson.

This is a very common phrase in Portuguese.

Examples:

• Ela dá aula de inglês. = She teaches English.
• Meu pai dá aula na universidade. = My father teaches at the university.

This is an important distinction:

• dar aula = to teach a class
• ter aula = to have a class / to attend class

So:

• A professora vai dar aula de português amanhã. = The teacher is going to teach Portuguese tomorrow.
• Os alunos vão ter aula de português amanhã. = The students are going to have Portuguese class tomorrow.

A native English speaker often needs to be careful here, because English uses have class and teach class, while Portuguese splits this clearly into ter and dar.

In this structure, de shows the subject of the class.

• aula de português = Portuguese class
• aula de matemática = math class
• aula de história = history class

So de português means the class is about / in the subject of Portuguese.

Yes, but it means something different.

• aula de português = a Portuguese-language subject class, a class about Portuguese
• aula em português = a class taught in Portuguese

So if the sentence says aula de português, it means the subject is Portuguese, not just that the language used in class is Portuguese.

In Portuguese, names of languages are normally not capitalized unless they begin a sentence.

So:

• português
• inglês
• espanhol

This is different from English, where Portuguese, English, and Spanish are capitalized.

Putting amanhã at the end is very natural in Portuguese. It works much like tomorrow at the end of an English sentence.

• A professora vai dar aula de português amanhã.

But Portuguese word order is fairly flexible, so you could also say:

• Amanhã, a professora vai dar aula de português.

That version puts more emphasis on tomorrow.

Yes, in many contexts Portuguese allows that because the verb often shows who the subject is. But here, vai could mean he/she/you depending on context, so keeping A professora makes the sentence clear.

For example:

• Vai dar aula de português amanhã.

This could be understood if everyone already knows who is being talked about, but by itself it is less clear than the full sentence.

No. Because dar aula clearly means to teach.

If you wanted to say that someone will attend or have a Portuguese class, you would normally use ter aula:

• A professora vai ter aula de português amanhã.

That would mean the teacher will have a Portuguese class, though in real life that would depend on context.

So in your sentence, the meaning is definitely teach.

Vai is the ele/ela/você form of the verb ir in the present tense.

Full present tense of ir:

• eu vou
• você/ele/ela vai
• nós vamos
• vocês/eles/elas vão

Since the subject is A professora = she / the teacher, the sentence uses vai.

No. In this sentence, português is just the name of the subject, so it appears without an article:

• aula de português
• aula de química
• aula de música

If you added an article, it would usually sound different or less natural in this basic school-subject meaning.

Very literally, it is:

• A professora = the teacher
• vai = goes / is going
• dar = to give
• aula = class / lesson
• de português = of Portuguese
• amanhã = tomorrow

So a very literal version would be:

The teacher is going to give a Portuguese class tomorrow.

But the natural English meaning is simply The teacher is going to teach Portuguese tomorrow or The teacher will teach Portuguese tomorrow.