Eu trouxe uma régua, uma lapiseira e um bloco para a aula de matemática.

You can very often leave Eu out in Portuguese.

Portuguese is a pro-drop language, so the verb form often already tells you who the subject is.
So Trouxe uma régua, uma lapiseira e um bloco para a aula de matemática is perfectly natural.

Including Eu can:

• add emphasis,
• make the subject extra clear,
• or contrast with someone else.

So:

• Eu trouxe... = slightly more explicit/emphatic
• Trouxe... = very natural in everyday Portuguese

Trouxe is the preterite (simple past) of trazer.

It is used for a completed action in the past: the bringing happened and is finished.

Here it means that the speaker brought those things on that occasion.

Because trazer is an irregular verb.

Its preterite does not follow a simple predictable pattern from the infinitive. The stem changes to troux-:

• eu trouxe
• tu trouxeste
• ele/ela/você trouxe
• nós trouxemos
• eles/elas/vocês trouxeram

So trouxe is something you simply have to learn as part of the verb’s past-tense forms.

No. Trouxe can mean:

• I brought
• he brought
• she brought
• you brought (formal você)

That is because in the preterite, eu and ele/ela/você share the same form: trouxe.

Context or the subject pronoun tells you which one is meant. In your sentence, Eu makes it unambiguously I brought.

Because Portuguese commonly repeats the indefinite article in a list when each item is being introduced as a separate object.

So this sounds natural:

• uma régua, uma lapiseira e um bloco

It makes the list clear and balanced.

You may sometimes see articles omitted in lists, but in a sentence like this, repeating them is very normal and standard.

Because Portuguese nouns have grammatical gender, and the article must agree with the noun:

• régua is feminine → uma régua
• lapiseira is feminine → uma lapiseira
• bloco is masculine → um bloco

A common pattern is:

• nouns ending in -a are often feminine
• nouns ending in -o are often masculine

But that is only a tendency, not a rule without exceptions.

In European Portuguese, lapiseira means a mechanical pencil or propelling pencil.

So it is not a normal wooden pencil, and it is definitely not a pen.

That word is very useful in school or office contexts.

Bloco literally means block, but in this kind of context it usually means a pad or notepad made of sheets of paper.

Depending on context, it could be:

• a notepad,
• a writing pad,
• a sketch pad,
• or some other paper block.

If you want to be more specific, Portuguese often adds another noun:

• bloco de notas = notepad
• bloco de desenho = drawing pad

Here, para means something like for or for/to the purpose of.

So para a aula de matemática means the items were brought for the maths lesson/class.

Breakdown:

• para = for / for the purpose of
• a aula = the class / the lesson
• de matemática = of maths / maths

This is a very natural way to express purpose in Portuguese.

Because after nouns like aula, school subjects are usually introduced with de + subject without an article.

So Portuguese normally says:

• aula de matemática
• aula de inglês
• professor de história

This is one of those patterns you should get used to as a chunk.

Using da matemática here would usually sound unnatural unless you were referring to some very specific, already-defined mathematics in a special context.

Yes. The sentence is flexible.

The version you have is the most neutral and natural:

• Eu trouxe uma régua, uma lapiseira e um bloco para a aula de matemática.

But you could move the phrase for emphasis:

• Para a aula de matemática, eu trouxe uma régua, uma lapiseira e um bloco.

That sounds like: As for maths class, I brought...

So the original order is the most straightforward, but not the only possible one.

Yes. This is standard list punctuation in Portuguese:

• uma régua, uma lapiseira e um bloco

Normally, Portuguese does not use a comma before e in a simple list, just as in many standard English styles.

So the punctuation in the sentence is completely normal.

They mainly help show stress and vowel quality.

• régua is stressed on the first syllable: RÉ-gua
• matemática is stressed on MÁ: ma-te-MÁ-ti-ca

The accents are important because they tell you how the word is pronounced and sometimes distinguish it from other possible stress patterns.

For learners, a good practical rule is:
if there is an accent mark, stress that syllable.

It is very natural.

It sounds like a normal, everyday sentence a student might say. The vocabulary is appropriate for Portugal, especially lapiseira, and the grammar is standard.

A native speaker of European Portuguese would have no problem with it at all.