Jamais vou esquecer isso.

In this sentence, jamais means never.

For a Brazilian Portuguese learner, the most useful comparison is:

• jamais = never, often more emphatic, dramatic, or formal
• nunca = never, the more common everyday choice

So:

• Jamais vou esquecer isso.
• Nunca vou esquecer isso.

Both mean the same thing, but nunca is usually more common in normal conversation in Brazil. Jamais can sound stronger, more emotional, or a little more literary depending on context.

Because Portuguese often drops subject pronouns when the verb already makes the subject clear.

Here, vou means I go / I am going, from ir, and in this structure it means I will. Since vou clearly shows first person singular, eu is optional:

• Eu jamais vou esquecer isso.
• Jamais vou esquecer isso.

Both are correct. Leaving out eu is very natural.

You might include eu for emphasis, contrast, or clarity, but it is not necessary here.

This is the ir + infinitive future structure, which is extremely common in Brazilian Portuguese.

• vou = I am going
• esquecer = to forget

Together, vou esquecer literally looks like I am going to forget, but in real usage it often just means I will forget.

So:

• Vou esquecer = I will forget / I’m going to forget

In this sentence:

• Jamais vou esquecer isso. = I will never forget that/this.

This is one of the most common ways to talk about the future in spoken Brazilian Portuguese.

Yes, absolutely.

• Jamais vou esquecer isso.
• Jamais esquecerei isso.

Both are correct.

The difference is mainly style and frequency:

• vou esquecer is more common in everyday Brazilian speech
• esquecerei is the simple future, which is correct but often sounds more formal, literary, or less conversational

A native speaker in Brazil is more likely to say:

• Nunca vou esquecer isso.

But Jamais esquecerei isso can sound very strong, dramatic, or elegant.

Putting jamais at the beginning gives it emphasis.

• Jamais vou esquecer isso.
• Nunca vou esquecer isso.

This is a very natural way to say never in Portuguese.

You can also hear other placements, such as:

• Não vou jamais esquecer isso.

But beginning the sentence with jamais sounds strong and clear. It highlights the idea of never right away.

So the beginning position is mostly about emphasis and style.

Not in this sentence.

Jamais can function by itself as a negative word, especially when placed before the verb:

• Jamais vou esquecer isso.

That is already negative. You do not need não.

Compare:

• Jamais vou esquecer isso. = correct
• Nunca vou esquecer isso. = correct

You may sometimes see or hear não with jamais, especially in different sentence structures:

• Não vou jamais esquecer isso.

That can also be correct, but in your sentence, jamais alone is enough.

Because esquecer can be used directly with an object.

Here, isso is the direct object:

• esquecer isso = forget that/this

This is very common and natural.

Portuguese also has a related form:

• esquecer-se de = to forget

For example:

• Eu me esqueci disso. = I forgot that.

So both patterns exist:

• esquecer algo
• esquecer-se de algo

In your sentence, the version used is the simpler direct-object structure:

• vou esquecer isso

That is completely normal.

Isso usually means that, and sometimes this, depending on context and how the meaning has been translated.

A simple practical way to think about it in Brazilian Portuguese:

• isto = this
• isso = that
• aquilo = that over there / that one

But in real Brazilian speech, isto is much less common, and isso often covers a lot of situations where English might use either this or that.

So Jamais vou esquecer isso is commonly understood as:

• I’ll never forget that
• sometimes I’ll never forget this

The exact English choice depends on context.

Yes. In everyday Brazilian Portuguese, isso is generally much more common than isto.

Even when traditional grammar might suggest isto, many Brazilians still prefer isso in casual speech.

So a sentence like:

• Jamais vou esquecer isso.

sounds very natural.

A sentence with isto is grammatically possible:

• Jamais vou esquecer isto.

But it often sounds more formal, written, or less common in everyday Brazilian conversation.

In Brazilian Portuguese, jamais is pronounced approximately like:

• zhah-MAIZH in many accents

A rough guide:

• j sounds like the s in measure or the zh sound
• final -ais sounds roughly like aiz, though the exact sound varies by accent

So the whole sentence is roughly:

• zhah-MAIZH voh es-keh-SAIR EE-soo

This is only an approximation for English speakers, but it can help as a starting point.

Yes, it is natural, but many Brazilians would more often say:

• Nunca vou esquecer isso.

Your original sentence:

• Jamais vou esquecer isso.

is also correct and natural, especially if the speaker wants to sound more emphatic, emotional, or dramatic.

So the most everyday version is probably:

• Nunca vou esquecer isso.

But jamais is still perfectly good Portuguese.

A word-by-word breakdown is:

• Jamais = never
• vou = I go / I am going
• esquecer = to forget
• isso = that / this

So literally it looks like:

• Never I-am-going to-forget that

Natural English:

• I will never forget that
• I’m never going to forget that

This is a good example of how Portuguese often uses ir + infinitive where English uses will or going to.

Yes. That is completely correct and very natural.

These are all possible:

• Jamais vou esquecer isso.
• Nunca vou esquecer isso.
• Eu jamais vou esquecer isso.
• Eu nunca vou esquecer isso.

The differences are mostly in tone:

• eu adds emphasis or clarity
• nunca sounds more everyday
• jamais sounds stronger or more expressive

For most casual conversation in Brazil, Eu nunca vou esquecer isso or Nunca vou esquecer isso would be very common.