Learn Hardcore Indonesian: Kami belajar tentang teknologi baru di perpustakaan.

kami = we (excluding the listener)
- Used when the speaker talks about their group, and the person being spoken to is not part of that group.
kita = we (including the listener)
- Used when the speaker and listener are in the same group.

In Kami belajar tentang teknologi baru di perpustakaan, the speaker is saying we (but not you) study/are studying….
If the listener were included, you would say: Kita belajar tentang teknologi baru di perpustakaan.

Does belajar mean study or learn, and do I need an object after it?

Belajar can mean both to study and to learn, depending on context.

Kami belajar. → We study / We are learning.
Kami belajar teknologi. → We study / are learning technology.

You can use belajar:

without an object: just the activity of studying/learning
with an object: what you are studying/learning

In this sentence, belajar tentang teknologi baru means study / learn about new technology. The object is the whole phrase tentang teknologi baru.

What does tentang mean, and is it always necessary with belajar?

Tentang means about (as in about a topic).

belajar teknologi → study technology
belajar tentang teknologi → study about technology

Both are possible:

Without tentang, it sounds a bit more direct: study technology.
With tentang, it emphasizes the topic, similar to study about / learn about.

So:

Kami belajar teknologi baru.
Kami belajar tentang teknologi baru.

Both are acceptable. The version with tentang feels slightly more explanatory or explicit about the topic.

Why is teknologi baru and not baru teknologi? Where do adjectives go?

In Indonesian, adjectives usually come after the noun.

teknologi baru = new technology (literally: technology new)
perpustakaan besar = big library
buku lama = old book

So the pattern is generally: noun + adjective, not adjective + noun.

Baru teknologi would sound wrong or, in some special contexts, could mean recently technology (not natural here). Stick to teknologi baru for new technology.

How do I know if teknologi baru means new technology or new technologies?

Indonesian usually does not mark singular vs. plural in the noun itself.

Teknologi baru can mean:

new technology (uncountable, general)
new technologies (plural, countable)

The number is understood from context. If you really need to be explicit:

banyak teknologi baru = many new technologies
satu teknologi baru = one new technology

Why is it di perpustakaan and not something like ke perpustakaan? What’s the difference?

di means at / in / on (location, where something happens).
ke means to (direction, movement toward a place).

In this sentence, the studying activity happens in the library, so you use di:

Kami belajar di perpustakaan. = We study in/at the library.

If you wanted to emphasize going there:

Kami pergi ke perpustakaan untuk belajar. = We go to the library to study.

Why is there no word like the before perpustakaan? How do I say the library vs a library?

Indonesian does not have articles like the or a/an.

Perpustakaan by itself can mean:

the library
a library
the libraries (in some contexts)
libraries

The exact meaning comes from context. If you need to be more specific:

perpustakaan itu = that / the library (specific)
sebuah perpustakaan = a library (one library, non-specific; more formal/literary)

Does this sentence mean We study technology in the library (habitually) or We are studying technology in the library right now?

By itself, Kami belajar tentang teknologi baru di perpustakaan is time-neutral. It can mean:

We study / learn about new technology in the library (a general/habitual statement)
We are studying / learning about new technology in the library (present, possibly right now)

Indonesian usually relies on context to clarify.
If you really want to emphasize right now / currently, you can add sedang:

Kami sedang belajar tentang teknologi baru di perpustakaan.
= We are currently studying / in the middle of studying new technology in the library.

Can I drop kami and just say Belajar tentang teknologi baru di perpustakaan?

Yes, you can drop kami if the subject is clear from context.

Indonesian often omits subject pronouns when they’re understood.
Belajar tentang teknologi baru di perpustakaan could mean:

(We) study about new technology in the library.
(I) study about new technology in the library.
(They) study about new technology in the library.

Spoken context or previous sentences usually make it clear.
If you want to be explicit that it’s we (not you), keep kami.

Is tentang the only way to say about here? Can I use mengenai or perihal instead?

Other words can also mean about / regarding, but their tone and usage differ:

tentang – the most common, neutral, works in everyday speech and writing.
mengenai – also means about / concerning, slightly more formal.
perihal – quite formal / literary, often in official documents.

You could say:

Kami belajar mengenai teknologi baru di perpustakaan.
(natural, slightly more formal)

But for everyday, tentang is usually the best choice.

Is belajar tentang teknologi baru di perpustakaan a single phrase modifying kami, or does di perpustakaan only attach to belajar?

Grammatically, the structure is:

Kami (subject)
belajar tentang teknologi baru (predicate: what we do)
di perpustakaan (adverbial phrase: where)

So di perpustakaan describes where the studying happens.
You can think of it as:

We study about new technology in the library.

It is not modifying kami, but the action (belajar).

How would I change this sentence to say We studied about new technology in the library yesterday?

You can add a time expression to show past:

Kami belajar tentang teknologi baru di perpustakaan kemarin.
= We studied / learned about new technology in the library yesterday.

Indonesian usually doesn’t change the verb form for past; instead, it uses time words like:

kemarin (yesterday)
tadi (earlier)
tadi pagi (this morning)
tahun lalu (last year), etc.