O professor vai explicar a última lição para nós amanhã.

In Portuguese, it is very common to use the definite article before nouns, including professions and people in general statements.

So o professor means the teacher/professor.

In English, you might say The teacher will explain..., but in some contexts English can also omit articles more freely than Portuguese. In Portuguese, professor by itself would usually sound incomplete here unless it were being used as a form of address, like Professor, pode ajudar?

Vai explicar is a very common way to express the future in Brazilian Portuguese.

It is made of:

• vai = goes / is going
• explicar = to explain

Together, vai explicar means is going to explain / will explain.

This is often more natural in everyday speech than the simple future:

• O professor vai explicar... = very common in conversation
• O professor explicará... = correct, but more formal or written

So this sentence is using the everyday spoken future.

Because the subject is O professor, which is third-person singular: he.

The verb ir changes to match the subject:

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

Since o professor = he/the teacher, the correct form is vai.

That a is the feminine singular definite article the.

It matches lição, which is a feminine singular noun:

• o livro = the book
• a lição = the lesson

So:

• a última lição = the last lesson

Both words are feminine singular:

• a = feminine singular article
• última = feminine singular form of último

Última usually means last in the sense of the last one in a sequence.

So a última lição means:

• the last lesson
• or sometimes the most recent lesson, depending on context

You could also hear lição final, but that often sounds more specifically like final lesson in a course or a more fixed label. In many everyday situations, última lição is the most natural choice for the last lesson.

Because para nós means to us / for us, and here it clearly marks who will receive the explanation.

• para = to / for
• nós = us / we

So:

• explicar a lição para nós = explain the lesson to us

You may also hear nos in some structures, but with explicar, Brazilian Portuguese very often uses para + pronoun:

• Ele explicou a lição para nós.

In everyday Brazilian speech, people also often say:

• para a gente

So you might hear:

• O professor vai explicar a última lição para a gente amanhã.

Because nós and nos are different words.

• nós = stressed pronoun, meaning we/us
• nos = unstressed object pronoun, meaning us

After a preposition like para, Portuguese uses the stressed pronoun:

• para mim
• para você
• para ele
• para nós

So para nós is correct.

You would not say para nos.

Yes. Portuguese allows some flexibility with adverbs like amanhã.

These are all possible:

• O professor vai explicar a última lição para nós amanhã.
• Amanhã, o professor vai explicar a última lição para nós.
• O professor vai explicar amanhã a última lição para nós.

The version with amanhã at the end sounds very natural and neutral.

Putting amanhã at the beginning can give it a little more emphasis, like Tomorrow, the teacher will explain...

Not exactly.

In Brazilian Portuguese, professor can refer to:

• a school teacher
• a university professor
• an instructor in general

In English, professor usually refers more specifically to a university teacher, while teacher is broader.

So in Portuguese, o professor may translate as either the teacher or the professor, depending on context.

Lição is pronounced approximately like lee-SOWN, with the stress on the last syllable.

A few useful points:

• li sounds like lee
• ção is a very common Portuguese ending
• -ção often corresponds to English -tion

Examples:

• lição = lesson
• informação = information
• nação = nation

In Brazilian Portuguese, -ção sounds roughly like sown with a nasal vowel at the end, not like an English shun sound.

Also note the accent mark in lição shows the stressed syllable.

They help show pronunciation and stress.

• última: the accent tells you the stress is on úl
  • ÚL-ti-ma
• lição: the accent helps indicate stress on the final syllable
  • li-ÇÃO

In Portuguese, accent marks are important because they often tell you where the stress goes and sometimes also signal vowel quality.

So they are not optional spelling marks; they are part of the correct written form.

Yes.

You could say:

• O professor explicará a última lição para nós amanhã.

This means the same thing, but it sounds more formal, written, or official.

Compare:

• vai explicar = very common, conversational, natural in everyday Brazilian Portuguese
• explicará = more formal, less common in casual speech

For a learner, vai + infinitive is extremely useful because Brazilians use it all the time.

Yes, usually.

• para nós sounds standard and neutral
• para a gente sounds more conversational and very common in Brazil

So all of these are possible, depending on tone:

• O professor vai explicar a última lição para nós amanhã.
• O professor vai explicar a última lição pra nós amanhã.
• O professor vai explicar a última lição pra gente amanhã.

Notes:

• pra is the spoken contraction of para
• pra gente is extremely common in everyday speech

If you are learning standard written Portuguese, para nós is an excellent form to know and use.