Eu vou copiar a frase no caderno.

In this context, frase means sentence.

That can confuse English speakers because it looks like phrase, but in Portuguese frase is often used for a complete sentence, especially in school contexts such as copying, reading, or writing exercises.

So in a classroom sentence like Eu vou copiar a frase no caderno, frase is very naturally understood as the sentence.

Yes, you can leave it out.

Portuguese is a pro-drop language, which means subject pronouns are often omitted when the verb already makes the subject clear. So both of these are natural:

• Eu vou copiar a frase no caderno.
• Vou copiar a frase no caderno.

Including eu can add:

• emphasis
• clarity
• contrast, as in I’m going to copy it, not someone else

So eu is not wrong at all, but it is often optional.

Vou copiar is the very common near future construction in Portuguese:
ir + infinitive

So:

• vou copiar = I am going to copy

This is extremely common in everyday speech in both Portugal and Brazil.

There is also a simple future form:

• copiarei

That is grammatically correct, but it usually sounds more formal, more written, or less conversational. In ordinary speech, vou copiar is much more natural.

Because after the verb ir in this future construction, Portuguese uses the infinitive of the main verb.

Pattern:

• vou + infinitive
• vais + infinitive
• vai + infinitive
• vamos + infinitive

Examples:

• Vou estudar.
• Vamos sair.
• Ela vai escrever.

So vou copiar follows a very normal pattern.

Because Portuguese usually uses an article before nouns in many places where English might or might not.

Here, a frase means the sentence. It refers to a specific sentence, probably one already known from the context, such as a sentence on the board or in a book.

Compare:

• a frase = the sentence
• uma frase = a sentence

Leaving out the article and saying just frase would generally not sound right in this sentence.

No is a contraction:

• em + o = no

So:

• no caderno = in the notebook

This kind of contraction is very common in Portuguese:

• em + a = na
• em + os = nos
• em + as = nas

Examples:

• no livro = in the book
• na escola = at/in the school
• nos cadernos = in the notebooks

So no caderno is just the normal contracted form of em o caderno, and em o is not used as separate words in standard Portuguese.

Because Portuguese normally uses em for the place where the writing appears.

With copiar, escrever, anotar, and similar verbs, em/no/na is very common to indicate the surface or place where something is written:

• escrever no caderno
• anotar no papel
• copiar no livro

Using para o caderno would sound more like movement toward the notebook, not the natural way to express writing something in it.

So no caderno is the idiomatic choice.

The given order is the most neutral and natural one:

• subject + verb + object + place

So:

• Eu vou copiar a frase no caderno.

But Portuguese does allow some flexibility. For example:

• Eu vou copiar no caderno a frase.

This is possible, but it sounds less neutral and may feel more marked or context-dependent.

For a learner, the safest and most natural order is the original one:

• Eu vou copiar a frase no caderno.

Yes, this is natural European Portuguese.

A speaker from Portugal might also very naturally omit the subject pronoun:

• Vou copiar a frase no caderno.

That version is probably even more common in everyday speech unless there is a reason to stress eu.

So the sentence is perfectly good for Portugal Portuguese.

In European Portuguese, some unstressed vowels are reduced, so the sentence may sound less fully pronounced than an English speaker expects.

A rough guide:

• Eu is often said very lightly.
• vou sounds roughly like voh
• copiar has the stress on the last syllable: co-pi-AR
• frase sounds more like FRAZ(uh) than a fully clear fra-ze
• caderno has stress on der: ca-DER-nu

So in connected speech, the whole sentence may sound more compact and reduced than the spelling suggests.

If you want a learner-friendly approximation, something like this can help:

eu vo cu-pi-AR a fraz nu ca-DER-nu

That is only approximate, but it reflects the general rhythm better than pronouncing every written vowel strongly.