Não entre no quarto agora, porque o chão está molhado.

Entre is the negative command form used with você (and also with o senhor / a senhora).

The base verb is entrar = to enter / to go in.

In Brazilian Portuguese, negative commands are formed with:

• não
  • the present subjunctive

So:

• você entra = you enter / you go in
• não entre = don’t go in

Why not the others?

• entrar is the infinitive: to enter
• entra is the positive command for tu in standard grammar, and also the present indicative for você/ele/ela depending on context
• entre is the correct negative command here

So Não entre means Don’t go in.

Negative commands in Portuguese are usually made with:

não + present subjunctive

Examples:

• Não fale. = Don’t speak.
• Não coma isso. = Don’t eat that.
• Não entre no quarto. = Don’t go into the room.

For the verb entrar, the present subjunctive forms are:

• eu entre
• você/ele/ela entre
• nós entremos
• vocês/eles/elas entrem

That is why the sentence uses não entre.

Yes. In this sentence, the speaker is addressing one person using the você form.

So Não entre means:

• Don’t go in (to one person)

If you wanted plural:

• Não entrem no quarto agora. = Don’t go into the room now.
  (addressing vocês)

If you were using standard tu grammar, it would be:

• Não entres no quarto agora.

In Brazil, though, você is extremely common, so não entre sounds very natural.

Because no is a contraction of:

• em + o = no

So:

• entrar no quarto = to go into the room

Other common contractions:

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

Examples:

• na casa = in/into the house
• nos carros = in the cars
• nas escolas = in the schools

Portuguese uses these contractions very regularly.

O quarto literally means the room, but in everyday Brazilian Portuguese, quarto very often means bedroom.

So depending on context, Não entre no quarto agora could mean:

• Don’t go into the room now
• Don’t go into the bedroom now

The article o is simply the masculine singular definite article: the.

The comma separates the command from the reason that follows.

• Não entre no quarto agora = the instruction
• porque o chão está molhado = the explanation

So the sentence structure is:

• command + comma + reason

This is very natural punctuation in Portuguese, just as in English you might write:

• Don’t go into the room now, because the floor is wet.

This is a very common question because Portuguese has several forms that look similar.

Here, porque means because, so it introduces a reason:

• Não entre... porque o chão está molhado.
• Don’t go in... because the floor is wet.

Quick guide:

• porque = because
• por que = why / for which reason
• por quê = why (usually at the end of a question)
• porquê = the reason (a noun)

Examples:

• Por que você saiu? = Why did you leave?
• Você saiu por quê? = You left why?
• Ninguém entendeu o porquê. = Nobody understood the reason.
• Saí porque estava cansado. = I left because I was tired.

Portuguese often uses estar for a temporary condition or current state, and ser for something more permanent or defining.

Here, the floor is wet right now, so:

• o chão está molhado = the floor is wet

Using ser would sound wrong in this context, because the floor is not inherently or permanently wet.

Compare:

• A porta está aberta. = The door is open.
• A porta é de madeira. = The door is made of wood.

So está molhado describes a current condition.

Because molhado agrees with o chão, and chão is a masculine noun.

• o chão = the floor
• molhado = wet (masculine singular)

Adjectives in Portuguese usually agree in gender and number with the noun they describe.

Examples:

• o chão molhado = the wet floor
• a camisa molhada = the wet shirt
• os pisos molhados = the wet floors
• as toalhas molhadas = the wet towels

Chão usually means floor or ground, depending on context.

In this sentence:

• o chão está molhado = the floor is wet

If you are indoors, chão is commonly understood as floor.

Some related words:

• chão = floor / ground
• piso = floor, flooring, surface of the floor
• solo = soil / ground (more formal or technical in many contexts)

So in this sentence, chão is the natural everyday word for floor.

Chão can be tricky for English speakers because of the nasal sound.

A rough approximation is:

• shown with a nasal ending
• IPA: /ʃɐ̃w̃/ in many Brazilian accents

Important points:

• ch in Portuguese sounds like sh
• ão is a nasal diphthong, very common in Portuguese

Other words with ão:

• não
• mão
• pão

This nasal sound does not exist in the same way in English, so it takes practice.

Yes, agora means now.

In this sentence:

• Não entre no quarto agora. = Don’t go into the room now.

Its placement is very natural after no quarto, but Portuguese word order can be somewhat flexible.

You might also hear:

• Agora não entre no quarto.

That version gives slightly different emphasis, more like:

• For now, don’t go into the room.

So agora means the same thing, but its position can change the focus a little.

In standard grammar, for a negative command to você, the expected form is:

• Não entre no quarto agora.

So this sentence is the standard and safest choice.

In informal spoken Brazilian Portuguese, you may hear people use forms that do not match formal grammar perfectly, depending on region and speech style. But for learning and for correct standard Portuguese, use:

• Não entre
• not Não entra

So if you want the grammatically correct negative command, Não entre no quarto agora is the right form.

Literally, yes, Portuguese uses entrar em something, which becomes entrar no / na / nos / nas after contraction.

So:

• entrar no quarto = literally enter into the room

In natural English, though, you would usually say:

• go into the room
• enter the room

So when translating, it is better to choose natural English rather than translate word for word.

Yes, depending on the situation.

Possible alternatives:

• Não entre no cômodo agora... = Don’t go into the room/space now...
  (cômodo is more general, less common in everyday speech for this exact sentence)
• Não entre no banheiro agora... = Don’t go into the bathroom now...
• ...porque o piso está molhado. = ...because the floor is wet.
  (piso sounds a bit more specific or slightly more formal than chão in some contexts)

But the original sentence sounds very natural and everyday:

• Não entre no quarto agora, porque o chão está molhado.

The original sentence already sounds natural. But in casual speech, people might say things like:

• Não entra no quarto agora, porque o chão tá molhado.
• Não vai pro quarto agora, que o chão tá molhado.

A few notes:

• tá is a very common spoken form of está
• pro = para o
• que can sometimes replace porque in casual speech when giving a reason

However, if you are learning standard Portuguese, the original version is excellent:

• Não entre no quarto agora, porque o chão está molhado.