Learn Hardcore Indonesian: Di bawah atap rumah tetangga, ada dinding ungu yang rapi. - Under the neighbor’s roof, there is a tidy purple wall.

Correct: Di bawah …, ada dinding … = “Under …, there is a wall …”
Don’t use adalah here. adalah links two noun phrases (e.g., Dia adalah guru = “He is a teacher”).
A more formal alternative to ada is terdapat.

Why does the sentence start with Di bawah atap rumah tetangga? Could that part go at the end?

Starting with the location is common and natural in Indonesian, especially with ada-sentences. You can also place the location at the end:

Ada dinding ungu yang rapi di bawah atap rumah tetangga. Both orders are fine; fronting the place phrase emphasizes location. The comma after the fronted phrase is optional.

What exactly does rumah tetangga mean? Is there a possessive marker for “neighbor’s”?

rumah tetangga literally “house neighbor” = “the neighbor’s house/a neighbor’s house.” Indonesian often shows possession with noun-noun sequences (possessed + possessor).

More specific: rumah tetangga saya (my neighbor’s house), rumah tetanggaku (colloquial “my neighbor’s house”), rumah tetangganya (his/her/their/the previously mentioned neighbor’s house).
You can also say rumah si tetangga (colloquial/pointed: “that neighbor’s house”).

Can I say atap tetangga instead of atap rumah tetangga?

Yes. atap tetangga = “the neighbor’s roof.” atap rumah tetangga literally “the roof of the neighbor’s house,” slightly more explicit but both are natural.

What’s the difference between dinding and tembok?

dinding: usually an interior wall/partition.
tembok: a thick outer wall (often masonry), or any big wall (compound wall, perimeter wall). In casual speech, people sometimes use them interchangeably, but the distinction above is the default.

Is dinding singular or plural here? How do I show plurals?

Indonesian doesn’t mark plural by default. ada dinding can mean “there is a wall” or “there are wall(s),” depending on context. To make it clearly plural:

Reduplication: dinding-dinding
Quantifiers: beberapa dinding (several walls), dua dinding (two walls)

Why is ungu after dinding? Do adjectives usually come after the noun?

Yes. The usual pattern is Noun + Adjective:

dinding ungu, rumah besar, baju baru With demonstratives, the order is Noun + Adjective + Demonstrative:
dinding ungu itu (that/the purple wall)

What is yang rapi doing here? Could I drop yang?

yang introduces a relative clause: yang rapi = “that/which is neat.” It attaches a descriptive predicate to the noun phrase.

dinding ungu yang rapi = “a purple wall that is neat” Without yang, dinding ungu rapi sounds off here. To stack two simple adjectives without yang, use coordination:
dinding ungu dan rapi (less common; yang feels smoother for “is neat”)

Could I say dinding yang ungu dan rapi instead?

Yes. Both are grammatical, with a slight nuance difference:

dinding ungu yang rapi: treats “purple” as a basic property and adds “that is neat” as a clause (often sounds a bit more natural).
dinding yang ungu dan rapi: presents both “purple” and “neat” inside one yang-clause, often used to select walls that have both properties.

Do I need sebuah to mean “a wall,” as in “there is a wall”?

No. Indonesian usually omits articles. Ada dinding … already works for “there is a wall.” You can add sebuah to emphasize singularity:

Ada sebuah dinding ungu yang rapi. Here buah is a general classifier; se- means “one.”

Is rapi the best word for a wall? What else can I use?

rapi = tidy/neat (no mess, well-ordered/finished). For walls, alternatives include:

bersih (clean)
halus (smooth)
terawat (well-maintained)
catnya rapi (the paintwork is neat) All depend on what quality you want to highlight.

Is atap the roof or the ceiling? What if I mean the inside of the house?

atap is the roof (outside covering). The ceiling is plafon or langit-langit.

Under the eaves/roof overhang: di bawah atap
Inside under the ceiling: di bawah plafon/langit-langit

What’s the difference between di bawah and ke bawah?

di bawah = at a lower location (“under/below”) — static position.
ke bawah = downward/to below — movement/direction. Here you need di bawah (location).

How do I pronounce tetangga? What’s with the double g?

Pronounce it roughly “te-tang-ga.” The ngg represents the velar nasal + hard g sound (/ŋg/), not two separate syllables “n + g.”

Is the comma after the fronted location phrase required?

No. It’s optional. Many writers omit it when the phrase is short:

Di bawah atap rumah tetangga ada dinding … (also correct)

Can I swap ada with terdapat here?

Yes. terdapat is a more formal/literary equivalent of ada in existential sentences:

Di bawah …, terdapat dinding … In everyday speech, ada is more common.

How do I use -nya for “the/its/their” here? Is di bawah atapnya okay?

Yes:

di bawah atapnya = “under its/the roof” (referring to a previously known roof) For “the neighbor’s roof,” include the possessor:
di bawah atap tetangganya / di bawah atap rumah tetangganya = “under his/her/their neighbor’s roof” Don’t split it as di bawahnya atap; attach -nya to the noun: atapnya.

Is there a difference between ungu and berwarna ungu/warna ungu?

ungu is the regular adjective: dinding ungu (purple wall).
berwarna ungu = “(is) colored purple,” a bit more formal/descriptive.
warna ungu is a noun phrase “the color purple,” used differently:
- Dinding itu berwarna ungu (The wall is purple)
- Less natural: dinding warna ungu (ok in ads/labels, but stylistically heavier)

Is it okay to write dibawah as one word?

No. The preposition di is written separately from location words:

Correct: di bawah
Incorrect: dibawah