Cậu làm phẳng bìa các tông nhé.

Cậu is a second-person pronoun meaning you, but it is not neutral in every situation.

In this sentence, it suggests:

• the speaker is talking to someone of a similar age,
• or someone younger,
• and the relationship is fairly familiar or casual.

It is common among friends, classmates, siblings, or people who are socially close.

So cậu làm phẳng... is roughly you flatten... / please flatten..., said in an informal, familiar way.

Yes. It is basically a request or mild command: Flatten the cardboard, please.

Vietnamese often does not need a special verb form for commands. Instead, the command feeling comes from:

• context,
• intonation,
• and particles such as nhé.

Without nhé, the sentence could sound more direct:

• Cậu làm phẳng bìa các tông.

With nhé, it becomes softer, like:

• please do that, okay?
• go ahead and do that for me, okay?

Nhé is a sentence-final particle that softens the tone and makes the sentence sound friendlier, gentler, or more persuasive.

In this sentence, it turns a direct instruction into something more like:

• Please flatten the cardboard, okay?
• Flatten the cardboard for me, alright?

It often adds a feeling of:

• friendliness,
• encouragement,
• seeking light agreement,
• or making a request less blunt.

It usually does not have a direct one-word English translation. Its job is more about tone than literal meaning.

Because phẳng is mainly an adjective meaning flat.

To express make something flat or flatten something, Vietnamese often uses:

• làm + adjective

So:

• phẳng = flat
• làm phẳng = make flat / flatten

This pattern is very common:

• làm sạch = clean, make clean
• làm nóng = heat, make hot
• làm mềm = soften, make soft

So làm phẳng bìa các tông literally means make the cardboard flat.

Bìa các tông means cardboard.

More literally:

• bìa can refer to stiff board, cover material, or cardboard-like material depending on context.
• các tông is a Vietnamese borrowing related to carton/cardboard.

Together, bìa các tông refers to cardboard material, especially sheets or pieces of cardboard.

In everyday Vietnamese, you may also see or hear:

• bìa carton
• thùng carton = cardboard box / carton box

So this sentence is talking about flattening a piece of cardboard, not necessarily a whole box unless context says so.

Vietnamese does not use articles like a, an, and the the way English does.

So bìa các tông can mean:

• cardboard
• the cardboard
• a piece of cardboard

The exact meaning depends on context.

If the speaker and listener already know which cardboard is meant, English would usually say the cardboard. If it is non-specific, English might say some cardboard or a piece of cardboard.

Vietnamese leaves that to context much more often than English does.

The word order is:

• Cậu = subject, you
• làm phẳng = verb phrase, flatten / make flat
• bìa các tông = object, cardboard
• nhé = sentence-final particle softening the request

So the structure is basically:

Subject + Verb + Object + Final particle

This is very common in Vietnamese.

Yes. Vietnamese often drops subjects when they are clear from context.

So a speaker could simply say:

• Làm phẳng bìa các tông nhé.

That would still mean:

• Please flatten the cardboard.

Including cậu makes the addressee explicit and can sound a bit more personal or contrastive, depending on the situation.

Both are possible, and usage varies.

You may hear:

• bìa các tông
• bìa carton

In modern everyday use, many speakers comfortably use carton in writing or speech, especially in phrases like:

• thùng carton = cardboard box

Bìa các tông is understandable and correct, but in some contexts bìa carton may sound more natural or more common to some speakers.

Yes. Depending on region and context, you may also hear:

• ép phẳng = press flat
• dàn phẳng = spread/flatten out
• làm dẹp = make flat, make flattened

But làm phẳng is clear, standard, and easy to understand.

The best choice depends on what exactly is happening:

• If you are smoothing something out, làm phẳng works well.
• If you are physically pressing it down, ép phẳng may sound more specific.

The overall tone is:

• informal,
• familiar,
• and polite in a soft way.

That tone comes from the combination of:

• cậu, which is casual and familiar,
• and nhé, which softens the instruction.

So it does not sound like a harsh order. It sounds more like:

• Could you flatten the cardboard, okay?
• Please flatten the cardboard.

Các tông is a Vietnamese adaptation of a foreign word related to carton.

The spelling reflects Vietnamese sound patterns and tone marking:

• các has a rising tone with the acute accent
• tông has the level ô vowel with the ngang tone

In practice, many learners will also encounter the non-fully-Vietnamized spelling carton, especially on packaging or in informal modern writing.

So if you see both các tông and carton, do not be surprised. They refer to the same basic idea.

Yes. Final particles can change the tone a lot.

For example:

• Cậu làm phẳng bìa các tông nhé.
  Friendly, soft request.

• Cậu làm phẳng bìa các tông đi.
  Still a request/command, but a bit more direct: Go ahead and flatten the cardboard.

• Cậu làm phẳng bìa các tông với.
  Colloquial, asking for help or favor, common in speech.

• Cậu làm phẳng bìa các tông nào.
  Encouraging tone, like come on, let’s do it or go ahead depending on context.

So nhé is one of the gentler and friendlier choices.