Kalau shift pagi selesai lebih cepat, kakak perempuan saya mampir ke minimarket untuk membeli yogurt lagi.

Here kalau is best understood as if: it introduces a condition.

• Kalau shift pagi selesai lebih cepat, ... = If the morning shift finishes earlier, ...

In everyday Indonesian, kalau can sometimes feel like when or whenever depending on context, but if is the safest reading in this sentence. A more formal alternative is jika.

Yes, shift is a loanword from English, and it is very commonly used in Indonesian for work schedules.

So shift pagi means morning shift in a very natural, everyday way. You could use more native-sounding expressions in some contexts, but shift is extremely common in speech and writing related to jobs.

Indonesian often leaves out possessives like her, his, or my when the meaning is already clear from context.

In this sentence, the listener naturally understands that the morning shift is your older sister’s shift, because the main clause is about kakak perempuan saya. So Indonesian does not need to say her morning shift explicitly.

English usually requires that possessive, but Indonesian often does not.

Selesai can behave like both an adjective and a verb-like predicate.

Here, shift pagi selesai means something like:

• the morning shift is finished
• the morning shift finishes / ends

Indonesian does not need a verb like is between the subject and selesai. So this structure is very normal.

Yes, lebih awal could also work.

• selesai lebih cepat = finishes faster / finishes sooner / finishes earlier
• selesai lebih awal = finishes earlier

In real usage, lebih cepat is very common and natural, even when English would probably say earlier. Lebih awal focuses more clearly on time on the clock, while lebih cepat can feel a little broader.

In Indonesian, possessives usually come after the noun.

So:

• kakak perempuan saya = my older sister
• literally: older-sibling female my

That is why saya comes at the end of the noun phrase, not at the beginning like my in English.

Kakak perempuan specifically means older sister.

• kakak = older sibling
• adik = younger sibling
• perempuan = female

So kakak perempuan saya is specifically my older sister.

By contrast, saudara perempuan is more like female sibling/sister in a more formal or less everyday style. In normal conversation, kakak perempuan is much more natural if you mean an older sister.

Not exactly. Mampir means stop by, drop in, or make a quick stop.

So mampir ke minimarket suggests that she is not just going there in a neutral way; she is making a brief stop there, often on the way somewhere or as a quick errand.

That nuance is different from simply saying pergi ke minimarket.

Because ke marks movement to a place, while di marks location at/in a place.

• mampir ke minimarket = stop by to the minimarket
• di minimarket = at the minimarket

Since the sentence describes going there, ke is the correct choice.

Yes, it could.

Untuk membeli means to buy / in order to buy, so it clearly expresses purpose:

• mampir ke minimarket untuk membeli yogurt lagi

This is a bit more complete and slightly more formal or neutral in tone.

In everyday speech, people often shorten it, for example:

• mampir ke minimarket beli yogurt lagi
• mampir ke minimarket buat beli yogurt lagi

So untuk membeli is correct and natural, but not the only possible wording.

Here lagi most naturally means again or more.

So the idea is that she is stopping by to buy yogurt again or to get more yogurt. The exact nuance depends on context:

• again = she had bought it before and is buying it once more
• more = she needs additional yogurt

Putting lagi at the end is very common in Indonesian.