Learn Hardcore Indonesian: Teman saya mengajak kami berfoto di taman setelah rapat. - My friend invites us to take photos in the park after the meeting.

Putting saya before the noun (saya teman) is not grammatical for possession. Saya can come before a noun only in other structures, for example as a subject:

Saya teman Andi. = I am Andi’s friend. (here saya is the subject, not a possessor)

What is the nuance of mengajak in this sentence? Is it the same as invite or ask?

Mengajak means to invite someone to do something together / to ask someone to join an activity.

Teman saya mengajak kami berfoto
= My friend invited/asked us to (join) take a photo.

Nuance:

It usually implies doing the activity together.
It is often used for casual, everyday invitations: going somewhere, doing something as a group.

Compare:

mengundang = to invite someone (more formal, often to an event: a wedding, a meeting, a party)
meminta = to ask/request (not necessarily to do something together; more about asking someone to do something for you)

Could I say Teman saya mengundang kami berfoto instead of mengajak?

No, that sounds unnatural.

Mengundang is used for inviting someone to an event or occasion, not to a specific simple action.
- Teman saya mengundang kami ke pesta. = My friend invited us to a party.
- Perusahaan mengundang kami ke rapat. = The company invited us to a meeting.

For inviting someone to do an activity together, use mengajak:

Teman saya mengajak kami berfoto. ✔️
Teman saya mengajak kami makan siang. ✔️

Why is there no untuk before berfoto? Can I say mengajak kami untuk berfoto?

Both forms are possible:

Teman saya mengajak kami berfoto. ✔️
Teman saya mengajak kami untuk berfoto. ✔️

The version without untuk is very natural and common in speech.
Adding untuk can sound a bit more explicit or slightly more formal, but the meaning is the same: to invite/ask us to take a photo.

Why is it kami and not kita? What is the difference?

Indonesian has two words for we / us:

kami = we/us (excluding the listener)
kita = we/us (including the listener)

In the sentence:

Teman saya mengajak kami berfoto…

The speaker is saying: My friend invited us (some group that does not include you, the listener) to take a photo…

If the listener was also included in the group, you would use kita:

Teman saya mengajak kita berfoto…
= My friend invited us (including you) to take a photo…

What exactly does berfoto mean? Is it the same as take a photo?

Berfoto literally means to take a photo / to be in a photo.

It is a verb formed with the prefix ber-, which often means to do something related to the root word.

foto = photo
berfoto = to take a photo / to pose for a photo

In practice, berfoto usually implies that you are in the picture, often posing:

Kami berfoto di taman.
= We took a photo in the park. (we are the people in the picture)

What is the difference between berfoto and mengambil foto?

Both can be translated as to take a photo, but the focus is slightly different:

berfoto
- Common in everyday speech.
- Emphasizes being in the photo or doing the activity of taking photos.
- Often neutral about whether you are the photographer or just posing.
mengambil foto
- More literally to take a photo (to take a picture).
- Slightly more technical; can emphasize the act of taking the shot (like the photographer).

Examples:

Kami berfoto di taman.
= We took a photo in the park. (posed for a picture)
Dia mengambil foto taman itu.
= He/She took a photo of that park. (emphasis on photographing the park)

Why is it di taman and not ke taman?

di = at / in / on (location)
ke = to (movement toward a place)

In this sentence, taman (the park) is the place where the action happens:

berfoto di taman = to take a photo in/at the park

If you wanted to talk about going to the park, you would use ke:

Kami pergi ke taman. = We went to the park.

Why is there no word for the or a before taman and rapat?

Indonesian generally does not use articles like the, a, or an.

So:

taman can mean a park or the park, depending on context.
rapat can mean a meeting or the meeting, depending on context.

In:

Teman saya mengajak kami berfoto di taman setelah rapat.

Natural translations:

My friend invited us to take a photo in the park after the meeting.
or
My friend invited us to take a photo in a park after a meeting.

Context decides which English article fits best, not the Indonesian sentence.

Can setelah rapat be placed somewhere else in the sentence?

Yes. Time expressions like setelah rapat (after the meeting) are quite flexible in Indonesian.

Possible positions:

At the beginning:
- Setelah rapat, teman saya mengajak kami berfoto di taman.
In the middle (original):
- Teman saya mengajak kami berfoto di taman setelah rapat.
Slightly earlier:
- Teman saya, setelah rapat, mengajak kami berfoto di taman. (possible but less common in speech; sounds more written or rhetorical)

All of these are grammatical; the difference is just in emphasis and style.

Could I say Teman saya mengajak kami foto di taman without ber-?

Typically, you should not drop ber- here.

Teman saya mengajak kami berfoto di taman. ✔️ (natural)
Teman saya mengajak kami foto di taman. ❌ (sounds wrong or incomplete in standard Indonesian)

You generally need a proper verb after mengajak:

mengajak kami berfoto
mengajak kami makan
mengajak kami bermain

There are slangy or very casual contexts where foto might be used like a verb, but in standard Indonesian you should use berfoto.

Is teman saya singular or plural? How would I say my friends?

Teman saya by itself is usually understood as my friend (singular).
To clearly say my friends (plural), Indonesians often repeat the noun:

teman-teman saya = my friends

So:

Teman saya mengajak kami berfoto…
= My friend invited us to take a photo…
Teman-teman saya mengajak kami berfoto…
= My friends invited us to take a photo…

Could I drop saya and just say Teman mengajak kami berfoto di taman setelah rapat?

You usually need saya (or another possessor) there.

Teman saya = my friend ✔️
Teman alone usually just means (a) friend in general, not clearly connected to the speaker.

Without saya, the subject becomes vague:

Teman mengajak kami berfoto…
= (Some) friend invited us to take a photo… (Who’s friend? From whose perspective?)

In natural speech, you almost always specify whose friend it is (teman saya, teman dia, teman kami, etc.) unless it is already very clear from context.

Is mengajak polite and formal enough to use after a meeting, or is it very casual?

Mengajak is neutral and can be used in both casual and reasonably formal contexts.

After a work meeting: Setelah rapat, manajer kami mengajak kami berfoto.
Among friends: Setelah rapat, teman saya mengajak kami berfoto.

If you want to sound more formal or distant, you might phrase things differently (for example, using mengundang for events), but for suggesting a group photo after a meeting, mengajak is perfectly natural and appropriate.