Nós ficamos de fazer outra faxina quando o guarda-roupa e o colchão já estiverem no lugar.

Ficar de + infinitive is a very common expression in Brazilian Portuguese. It means something like:

• to agree to do
• to arrange to do
• to say that we would do

So Nós ficamos de fazer outra faxina means we agreed to do another cleaning or we said we’d do another cleaning.

This is not the literal idea of to stay or to remain, even though ficar often has those meanings in other contexts.

Ficamos is the preterite form of ficar, so it refers to a completed action in the past: the agreement was made already.

Here, the sentence is talking about two times:

1. Past: Nós ficamos de fazer... = we made the agreement.
2. Future: quando ... estiverem no lugar = when the wardrobe and mattress are in place.

So the structure is:

• first, we agreed
• later, we will do the cleaning

If you said ficaremos, it would mean we will agree, which changes the meaning.

Because ficar in this idiomatic meaning normally uses the pattern:

ficar de + infinitive

Examples:

• Fiquei de ligar amanhã. = I said I’d call tomorrow.
• Eles ficaram de trazer as cadeiras. = They agreed to bring the chairs.

So in your sentence:

• ficamos de fazer = we agreed to do

The de belongs to the expression. You generally should learn ficar de as a set phrase.

They are related, but not always identical.

• limpeza = cleaning in a broad/general sense
• faxina = a more thorough cleanup, often a bigger or more deliberate cleaning session

So fazer uma faxina often suggests:

• tidying up
• sweeping, mopping, dusting
• putting things in order
• doing a proper cleanup

In many situations, faxina sounds more natural than limpeza when talking about cleaning the house.

So outra faxina suggests another round of cleaning / another proper cleanup.

Both are possible, but outra faxina is very natural and common.

In Portuguese, outro/outra often appears without an article:

• outra vez = another time
• outro dia = another day
• outra ideia = another idea

So fazer outra faxina is perfectly normal.

If someone said fazer uma outra faxina, it would still be understandable, but it is usually less direct and often unnecessary here.

Because Portuguese often uses the future subjunctive after quando when talking about a future event that has not happened yet.

Here, the meaning is:

• when the wardrobe and the mattress are already in place

Since that situation is still in the future, Portuguese uses:

• quando ... estiverem

This is very common after words like:

• quando = when
• se = if
• assim que = as soon as
• depois que = after

Examples:

• Quando eu chegar, te ligo. = When I arrive, I’ll call you.
• Se eles puderem, vão ajudar. = If they can, they’ll help.

So estiverem is not random—it is the expected form here.

Because each form does a different job:

• estiverem = future subjunctive
• estarem = personal infinitive
• estarão = simple future indicative

After quando referring to a future condition/event, Portuguese normally prefers the future subjunctive:

• quando estiverem no lugar

Using estarão after quando in this kind of sentence sounds unnatural in standard Portuguese.

Using estarem would also not fit this structure.

So this is one of those patterns that learners need to get used to:

• quando + future subjunctive

Because together they form a compound subject:

• o guarda-roupa e o colchão

That means the verb must be plural, because the subject is the wardrobe and the mattress.

So:

• o guarda-roupa = singular
• o colchão = singular
• o guarda-roupa e o colchão = plural

That is why the sentence uses:

• estiverem = they are / will be

No lugar literally means in the place, but in this context it usually means:

• in place
• where they belong
• properly set/positioned

So quando o guarda-roupa e o colchão já estiverem no lugar means that those items have already been moved or positioned where they are supposed to go.

It does not necessarily mean just in the room. It suggests they are already set up in their proper spot.

Já here means already.

It adds the idea that before the new cleaning happens, the wardrobe and mattress should already be in place.

Compare:

• quando estiverem no lugar = when they are in place
• quando já estiverem no lugar = when they are already in place

In this sentence, já helps show sequence:

1. put the wardrobe and mattress in place
2. then do another cleaning

Yes. In Brazilian Portuguese, subject pronouns are often optional when the verb already makes the subject clear.

So these are both natural:

• Nós ficamos de fazer outra faxina...
• Ficamos de fazer outra faxina...

Because ficamos clearly shows we, the sentence works without nós.

Including nós can add:

• emphasis
• clarity
• contrast

So the version with nós is not wrong at all—it may simply sound a bit more explicit.

Guarda-roupa means wardrobe or closet/armoire, depending on the context.

It is a compound noun:

• guardar = to keep/store
• roupa = clothes

Even though it comes from two parts, you should treat guarda-roupa as one noun.

A useful detail: in Brazilian Portuguese, guarda-roupa is usually masculine in this meaning:

• o guarda-roupa

So the sentence correctly says:

• o guarda-roupa e o colchão

Yes, fazer faxina is very common and natural in Brazilian Portuguese.

Portuguese often uses fazer with nouns to express actions:

• fazer uma pergunta = ask a question
• fazer uma viagem = take a trip
• fazer faxina = do a cleaning / clean up

Even if English might prefer a simple verb like clean, Portuguese often likes the fazer + noun structure.

So fazer outra faxina sounds very idiomatic.

Yes. A Brazilian speaker might also say similar things such as:

• Combinamos de fazer outra faxina quando o guarda-roupa e o colchão já estiverem no lugar.
• Vamos fazer outra faxina quando o guarda-roupa e o colchão já estiverem no lugar.

But each version is slightly different:

• ficamos de fazer = we agreed / we said we would
• combinamos de fazer = we arranged / agreed
• vamos fazer = we’re going to do

Your original sentence is natural and emphasizes the prior agreement.