Primeiro separamos o papelão; depois descartamos o rejeito.

Because both verbs are in the 1st person plural of the present indicative:

• separamos = we separate
• descartamos = we discard

In Portuguese, the ending -amos often marks we with -ar verbs.

The full forms are:

• separar → nós separamos
• descartar → nós descartamos

Portuguese often drops the subject pronoun nós because the verb ending already shows who is doing the action.

Portuguese is a language that often omits subject pronouns when the verb ending makes the subject clear.

So:

• Primeiro separamos o papelão
  means the same as
• Primeiro nós separamos o papelão

Both are correct, but leaving out nós sounds natural and common.

Yes. In Portuguese, separamos can mean either:

• we separate or we are separating (present)
• we separated (simple past / preterite)

The form is the same for -ar verbs in nós.

Context tells you which meaning is intended. In this sentence, with Primeiro... depois..., it usually sounds like a procedure or instructional description, so we separate / first we separate is the most natural reading.

They are sequence markers:

• primeiro = first
• depois = afterwards / then

Putting them at the beginning helps organize the steps clearly:

• Primeiro separamos o papelão;
• depois descartamos o rejeito.

This is very common in explanations, instructions, and process descriptions.

The semicolon links two closely related parts of the same idea:

• Primeiro separamos o papelão; depois descartamos o rejeito.

It shows a stronger break than a comma, but a closer connection than a full stop.

You could also see:

• Primeiro separamos o papelão. Depois descartamos o rejeito.
• Primeiro separamos o papelão, depois descartamos o rejeito.

All are understandable. The semicolon is just a neat, formal way to connect the two steps.

O is the masculine singular definite article, meaning the.

Here it appears before both nouns:

• o papelão
• o rejeito

In Portuguese, articles are used more often than in English. Even when speaking in a general or practical way, Portuguese often prefers the article.

So o papelão is natural where English might simply say cardboard.

Papelão means cardboard.

It is different from:

• papel = paper
• papelão = cardboard

The ending -ão is part of the noun itself here, not a grammar ending you can freely attach to other words.

Not exactly.

• lixo = trash, garbage, general waste
• rejeito = reject waste, unusable residue, material that cannot be reused or recycled

In recycling or waste-management contexts, rejeito is more specific than lixo. It refers to what remains after sorting and cannot be recovered.

So in this sentence, o rejeito means something like the residual waste or the non-recyclable waste.

Descartar is a more formal and technical verb, especially common in environmental, recycling, and procedural contexts.

Compare:

• descartar o rejeito = dispose of the residual waste
• jogar fora o lixo = throw away the trash

Both can be correct, but descartar sounds more appropriate in an instructional or waste-sorting context.

It can sound instructional in context, but grammatically the sentence is in the indicative, not the imperative.

What it literally says is:

• First we separate the cardboard; then we discard the waste.

Portuguese often uses we in procedural explanations, similar to English instructions like First, we add the sugar.

If you wanted a more direct command, you could say:

• Primeiro, separe o papelão; depois, descarte o rejeito.

That would be a clearer you command.

No, Portuguese allows some flexibility, though the original order is very natural.

Original:

• Primeiro separamos o papelão; depois descartamos o rejeito.

You could also say:

• Separamos o papelão primeiro; depois descartamos o rejeito.
• Depois descartamos o rejeito, mas primeiro separamos o papelão.

The original version sounds clear and organized because it presents the steps in order.

In Brazilian Portuguese, papelão is pronounced approximately like:

• pah-peh-LOWN

But the final -ão is nasal, which English does not really have.

A rough guide:

• pa = like pah
• pe = like peh
• lão = a nasal sound, somewhat like lown said through the nose

The stress is on the last syllable:

• pa-pe-LÃO

That final -ão is very common in Portuguese, and learning its nasal quality is important.

Here it works like a collective or mass noun: it does not need to refer to one single object.

So o rejeito can mean the reject material / the residual waste in a general sense, not necessarily one piece of waste.

This is similar to how English might say:

• the waste
• the residue
• the garbage

even when referring to a whole category rather than one item.