Learn Hardcore Indonesian: Kantin kampus menjual bakso hangat; saya sesekali membelinya setelah kuliah. - The campus canteen sells warm meatball soup; I occasionally buy it after class.

Yes. Kantin kampus is a compact noun–noun phrase that works like a possessive (campus canteen). Kantin di kampus is also correct and highlights location (a canteen located on campus). Both are natural; the compound feels tighter and more formal.

Why is it menjual and not just jual? And similarly membeli vs beli?

The prefix meN- turns a root into a standard active verb:

jual → menjual (to sell), beli → membeli (to buy) Using the bare roots (jual, beli) is common in casual speech. With meN- you sound more neutral/formal and clearly transitive.

How does the meN- prefix change with different first letters?

It assimilates to the first sound of the root:

mem- before b/p/f/v (p drops): beli → membeli, pakai → memakai
men- before d/t/c/j (t drops): tulis → menulis, jual → menjual, cuci → mencuci
meng- before k/g/h and vowels (k drops): kirim → mengirim, ajar → mengajar
meny- before s (s drops): sapu → menyapu
me- before l/r/w/y: lihat → melihat, rawat → merawat

What does -nya in membelinya mean?

It’s a third-person object clitic meaning it/them, referring back to bakso. So saya sesekali membelinya = I occasionally buy it/them. It also signals definiteness (the previously mentioned item).

Is -nya singular or plural? Why not use mereka for them?

-nya is number-neutral for things; English may translate it as it or them depending on context. Mereka is only for people, so not for bakso. For emphasis you could say membeli bakso itu (buy that bakso).

Why is it bakso hangat and not hangat bakso?

Attributive adjectives follow the noun in Indonesian: bakso hangat (warm bakso). Hangat bakso is ungrammatical as a noun phrase, though as a sentence you can say Bakso itu hangat (That bakso is warm).

How would bakso yang hangat differ from bakso hangat?

Bakso hangat simply describes the bakso as warm. Bakso yang hangat is more like the bakso that is warm, used to pick out specific warm ones among others or to add emphasis.

Where can I put sesekali? Is Saya membelinya sesekali okay?

All of these are acceptable:

Saya sesekali membelinya (neutral)
Sesekali saya membelinya (slight focus on frequency)
Saya membelinya sesekali (also fine; often heard in speech) You can swap in kadang-kadang (sometimes, more frequent) or sekali-sekali/sesekali (once in a while, less frequent).

Does setelah kuliah mean after class or after finishing college?

Here it means after class/lecture. To mean after finishing college, say setelah lulus kuliah or setelah selesai kuliah.

What’s the difference between setelah, sesudah, and habis/sehabis?

Setelah and sesudah are near-synonyms (after), with setelah a bit more formal. Habis/sehabis is more colloquial: Habis kuliah, saya beli bakso.

Is the semicolon natural here?

Yes, a semicolon is fine in formal writing. In everyday writing people often use a period: Kantin kampus menjual bakso hangat. Saya sesekali membelinya setelah kuliah.

Indonesian has no articles. How do I say the canteen vs a canteen?

Context decides. You can mark definiteness with itu or -nya:

kantin kampus itu (that/the campus canteen)
kantinnya (the canteen, its canteen—context determines which)

Could I make it passive, like Bakso hangat is sold at the campus canteen?

Yes: Bakso hangat dijual di kantin kampus. You can add an agent: … oleh kantin kampus, though it’s often omitted.

How do I talk about quantity with bakso?

Common measures:

seporsi bakso / semangkuk bakso (a portion/bowl of bakso)
tiga butir bakso (three meatballs, counting the balls)
beberapa bakso (some meatballs)

Why use saya here? Could I use aku?

Saya is neutral/formal and safe in writing or with strangers. Aku is informal/intimate with friends/family. In Jakarta slang you’ll hear gue/gua.