Learn Hardcore Indonesian: Dia baru saja menerima file itu, jadi kelompok mulai berdiskusi. - He just received that file, so the group starts to discuss.

Yes. Dia is a gender-neutral third-person singular pronoun, so it can mean he or she (and sometimes it is used for animals). For a respectful reference to an older or highly respected person, use beliau. In formal writing, ia is also common, especially as a subject pronoun. Example: Ia baru saja menerima...

Why use baru saja? Could I just say baru? What about barusan or tadi?

baru saja = just now, very recently (neutral).
baru alone can mean either just/recently or only, so it’s a bit more ambiguous. In many contexts it still reads as “just,” but baru saja removes ambiguity.
barusan = just now, very recent (colloquial).
tadi = earlier (today), not necessarily “just now.” So: Dia baru saja menerima... and Dia barusan menerima... are near-equivalents; Dia tadi menerima... means they received it earlier today; Dia baru menerima... could be “just received” or “only then received,” depending on context.

Does saja mean “only” here?

In baru saja, saja intensifies the sense of recency (“just now”). On its own, saja can mean “only/just/simply,” but here it doesn’t mean “only.” To say “only,” prefer hanya: Dia hanya menerima file itu. In casual speech, saja often becomes aja: baru aja.

What’s the base form of menerima? Could I just use terima as a verb?

The root is terima. With the active prefix meN-, it becomes menerima (“to receive/accept”). The initial t drops and the prefix surfaces as men-: meN- + terima → menerima. The passive is diterima (“be received”). Bare terima is not normally used as a standalone verb in standard Indonesian (except in the fixed expression terima kasih). In casual speech you may hear nerima (colloquial).

What exactly does file itu mean? Is itu like “the” or “that,” and why does it come after the noun?

Itu is a demonstrative meaning “that,” and it follows the noun: file itu = “that file” or “the file (already known/mentioned).” Indonesian demonstratives are post-nominal: buku itu (that/the book), buku ini (this book). For a very formal “the aforesaid,” use tersebut: file tersebut.

Is file the normal word? What about berkas or dokumen?

file is very common in tech/digital contexts (a computer file).
dokumen is a document (digital or paper).
berkas is a dossier/folder/collection of documents (more administrative).
arsip is an archive/archival record. Note: In Indonesian it’s spelled file; in Malay you’ll often see fail. Pronunciation in Indonesian is typically like English “file.”

Why is there a comma before jadi? Is that standard?

Yes. When jadi links two independent clauses, a comma before it is common: ..., jadi .... If jadi starts a sentence, you normally put a comma after it: Jadi, .... Some style guides even allow a semicolon before jadi for a slightly more formal look: ...; jadi, ....

What exactly does jadi mean here, and how does it differ from karena itu, makanya, maka, or sehingga?

jadi = so/therefore (neutral, very common in speech and writing).
karena itu = therefore/for that reason (more formal).
makanya = that’s why (colloquial).
maka = hence/therefore (formal/literary).
sehingga = as a result/so that; typically used after the cause: Dia terlambat, sehingga rapat ditunda. In this sentence, jadi nicely introduces the result clause.

Is it okay that the subject changes from dia to kelompok in the second clause?

Yes. Indonesian freely switches subjects across clauses if the meaning is clear. Here, the first clause’s subject is the individual (dia), and the result involves the group (kelompok). If you meant that the same person started discussing, you’d repeat dia: ..., jadi dia mulai berdiskusi.

Should it be kelompok itu instead of just kelompok?

Both are possible. Bare kelompok can still refer to a specific group if context is clear. Kelompok itu explicitly marks “that group/the group in question,” which can sound a bit more specific or formal.

What’s the difference between kelompok, grup, and tim?

kelompok = group/cluster (general, neutral Indonesian).
grup = group (loanword; common for bands, chat groups, social media groups).
tim = team (task-oriented, sports, work). All can be correct depending on context; kelompok is the safest general term.

What’s the difference between mulai and memulai?

mulai is intransitive or used before a verb: kelompok mulai berdiskusi (the group begins to discuss), mulai hujan (it starts to rain).
memulai is transitive and takes a direct object: kelompok memulai diskusi (the group starts the discussion). So your sentence is correct with mulai berdiskusi. If you switch to a noun object, use memulai: memulai diskusi.

Can I say mulai diskusi instead of mulai berdiskusi?

It’s heard in casual speech, but standard usage prefers:

Verb: mulai berdiskusi (“begin to discuss”)
Noun object: memulai diskusi (“begin the discussion”) So avoid mulai diskusi in careful writing.

What does the prefix ber- do in berdiskusi?

ber- often forms intransitive verbs meaning “to engage in/do X” or reciprocal actions. diskusi (discussion, noun) → berdiskusi (to discuss, to have a discussion). Contrast with mendiskusikan (transitive: to discuss something): mendiskusikan rencana itu.

Could I use mendiskusikan here instead of berdiskusi?

Yes, but then you need an object: ..., jadi kelompok mulai mendiskusikan file itu/masalah itu. Without an object, mendiskusikan sounds incomplete. Berdiskusi needs no object.

How would a more formal version look?

For a formal tone:

Ia baru saja menerima berkas tersebut, sehingga kelompok itu mulai berdiskusi. If you replace “just now,” note that telah/sudah indicate completion, not recency: Ia telah/sudah menerima berkas tersebut, sehingga... (more formal but loses the “just now” nuance).

How would a casual spoken version sound?

Dia baru aja nerima file itu, jadi mereka mulai diskusi.
Dia barusan nerima file itu, jadi kelompoknya mulai berdiskusi. Colloquial features: aja for saja, nerima for menerima, sometimes mulai diskusi in speech.

Can I move baru saja around?

Yes:

Dia baru saja menerima file itu (most natural).
Baru saja dia menerima file itu, ... (fronted for emphasis on timing).
File itu baru saja dia terima, ... (object-fronting; common and natural). Avoid splitting it awkwardly: Dia menerima baru saja file itu is unnatural.

Is there ambiguity between baru meaning “new” and “just”?

Context resolves it. As an adjective, baru = new: file baru (a new file). As an adverb, baru = just/recently: Dia baru menerima file itu. In baru saja, it clearly means “just now,” not “new.”

Could the first clause be made passive?

Yes:

File itu baru saja diterimanya, jadi kelompok mulai berdiskusi.
File itu baru saja diterima oleh dia, ... (more explicit but less natural than the enclitic -nya). You can also use object-fronting with an active base verb in colloquial style: File itu baru saja dia terima, ...