A parede da sala ficou por pintar, porque o pintor notou uma fenda perto do rodapé.

It means that the wall was left unpainted or remained to be painted.

This is a very natural Portuguese way to express that something was not done in the end, often because something prevented it. So the idea is not just it was unpainted, but more specifically it ended up not getting painted.

Ficar por + infinitive is a common pattern meaning to remain left to do or to not get done.

So:

• ficou por pintar = was left to paint / remained unpainted
• ficou por fazer = was left undone
• ficou por dizer = was left unsaid

In English, this often sounds more natural as a passive idea:

• A parede ficou por pintar = The wall was left unpainted

Ficou is the preterite of ficar, and here it suggests a result or outcome: the wall ended up unpainted.

Compare:

• ficou por pintar = it ended up not being painted
• estava por pintar = it was still to be painted / it was unpainted at that time

So ficou fits well because the sentence describes what happened after the painter noticed the crack.

Both are in the pretérito perfeito simples, which is usually called the preterite or simple past in English explanations.

• ficou = he/she/it stayed / ended up / remained
• notou = he/she noticed

This tense is used for completed past events, which is exactly what we have here: the painter noticed something, and as a result the wall was left unpainted.

Da is a contraction of de + a.

So:

• de a sala becomes da sala

Here it means of the room or of the living room, depending on context.

So:

• a parede da sala = the wall of the room / the living-room wall

Portuguese uses these contractions all the time, so you should think of da as a normal, required form rather than something optional.

Portuguese uses definite articles more often than English, especially with specific nouns.

In this sentence:

• a parede = the wall
• da sala = of the room (de + a)
• o pintor = the painter
• do rodapé = of the skirting board/baseboard (de + o)

English often drops articles where Portuguese keeps them, so this is something English speakers need to get used to.

Fenda means crack, fissure, or split.

In this sentence, it suggests a crack in the wall near the skirting board.

It is similar to racha, but there can be a slight difference in tone:

• fenda often sounds a bit more neutral or slightly more technical
• racha can sound more everyday and can suggest a more obvious crack or split

In many contexts, both could work, but fenda is a very good choice in a sentence about a wall defect.

Rodapé means skirting board in British English or baseboard in American English.

Do is the contraction of de + o:

• perto de o rodapé becomes perto do rodapé

So:

• perto do rodapé = near the skirting board / baseboard

This kind of contraction is mandatory in standard Portuguese.

Yes. Some natural alternatives are:

• junto ao rodapé = next to the skirting board
• ao pé do rodapé = at the foot of / right by the skirting board
• próximo do rodapé = close to the skirting board

In your sentence, perto do rodapé is completely natural and easy to understand.

Usually, no. In many cases, Portuguese would simply write:

A parede da sala ficou por pintar porque o pintor notou uma fenda perto do rodapé.

When the porque clause comes after the main clause, the comma is often omitted. If a comma appears, it may reflect a pause, a stylistic choice, or extra emphasis on the explanation.

So the version with the comma is understandable, but many native speakers would probably write it without one.

Because here it is a conjunction meaning because.

Portuguese distinguishes several similar forms:

• porque = because
• porquê = the reason / the why
• por que = often why or for which
• por quê = used at the end of a question

In your sentence, it introduces the cause, so porque is the correct spelling.

Not in this sentence, because the meaning would change.

• por pintar = left to be painted / still unpainted
• para pintar = to paint / for painting / in order to paint

So:

• ficou por pintar = was left unpainted
• ficou para pintar can sometimes mean was left for painting later, which is close in some contexts, but not exactly the same
• para pintar by itself does not naturally express the idea of not having been done

So por pintar is the best choice here.