Di minimarket dekat kos, adik perempuan saya mencari yogurt dan biskuit untuk sarapan besok.

Indonesian often allows a place phrase to come first if the speaker wants to set the scene first. So:

Di minimarket dekat kos, adik perempuan saya mencari yogurt dan biskuit untuk sarapan besok.

literally starts with At the minimarket near the boarding house/rented room...

This is natural in Indonesian. You could also say:

Adik perempuan saya mencari yogurt dan biskuit di minimarket dekat kos untuk sarapan besok.

That version is also grammatical, but it puts the subject first instead of the location.

Di is a preposition meaning in, at, or on, depending on context. Here, di minimarket means at the minimarket.

A very important point for learners:

• di
  • noun = preposition
    
    • di rumah = at home
    • di minimarket = at the minimarket

This is different from the prefix di- used in passive verbs:

• dibeli = bought
• dicari = searched for / looked for

So spacing matters:

• di minimarket = at the minimarket
• dibeli = bought

Kos refers to a boarding house, rented room, or student lodging, especially common in Indonesia. It usually means a simple place someone rents to live in, often just a room.

So dekat kos means near the boarding house / near the place where someone rents a room.

This is a very common everyday Indonesian word, especially in student or urban life.

Because dekat can be used directly before a noun in Indonesian.

So these are both possible:

• dekat kos = near the boarding house
• dekat dengan kos = near the boarding house

But dekat kos is shorter and very natural in everyday speech.

You can think of dengan here as optional in many cases.

It most naturally means my younger sister.

Breakdown:

• adik = younger sibling
• perempuan = female
• saya = my

So:

• adik saya = my younger sibling
• adik perempuan saya = my younger sister
• adik laki-laki saya = my younger brother

Indonesian often builds meanings this way by combining words rather than using a single exact equivalent.

In Indonesian, possession usually comes after the noun.

So:

• adik perempuan saya = my younger sister
• literally: younger sister my

This is a very common Indonesian pattern:

• rumah saya = my house
• teman saya = my friend
• buku saya = my book

So if you are an English speaker, remember that Indonesian often says noun + possessor, not possessor + noun.

Mencari is the standard active verb form meaning to look for or to search for.

• cari is the root
• mencari is the more complete verb form

In a full written sentence, mencari is usually the better choice.

Compare:

• Saya mencari biskuit. = I am looking for biscuits.
• Saya cari biskuit. = also common, especially in casual speech, but less formal

So mencari sounds more standard and polished.

Indonesian nouns usually do not change form for singular vs. plural.

So:

• biskuit can mean a biscuit, biscuits, or some biscuits
• yogurt can mean yogurt, a yogurt, or some yogurt, depending on context

Context tells you whether it is singular or plural.

If needed, Indonesian can show plurality in other ways, such as:

• beberapa biskuit = several biscuits
• biskuit-biskuit = biscuits

But often this is unnecessary.

Because Indonesian does not have articles like English a/an and the.

So:

• minimarket can mean a minimarket or the minimarket
• biskuit can mean a biscuit, the biscuit, or biscuits

The listener understands from context.

This is one reason Indonesian sentences can look shorter and simpler than English ones.

It means for tomorrow's breakfast or for breakfast tomorrow.

Breakdown:

• untuk = for
• sarapan = breakfast / to have breakfast
• besok = tomorrow

So the phrase tells us the purpose of buying or looking for the food: it is intended for breakfast the next day.

In this sentence, sarapan besok works like tomorrow's breakfast.

So:

• untuk sarapan besok = for tomorrow's breakfast

If you said besok sarapan, that more naturally sounds like tomorrow, (someone) has breakfast or it could feel less tightly connected as a noun phrase.

In other words:

• sarapan besok = breakfast tomorrow / tomorrow's breakfast
• besok is modifying the breakfast time

Yes, minimarket is commonly used in Indonesian, even though it comes from English. It refers to a small convenience-store-type shop.

Indonesian uses many loanwords, and this is a very normal everyday one.

Likewise:

• yogurt is also a borrowed word
• biskuit comes from a foreign source too, but it is fully established in Indonesian spelling

It sounds neutral to fairly standard.

Why:

• saya is more neutral/formal than aku
• mencari is more standard than just cari
• the sentence structure is clear and natural for writing or careful speech

But it is not overly formal. It still sounds like ordinary modern Indonesian.

A more casual version might be:

Di minimarket dekat kos, adik perempuan aku cari yogurt dan biskuit buat sarapan besok.

That sounds more informal because of:

• aku instead of saya
• buat instead of untuk
• cari instead of mencari

Yes, Indonesian word order is somewhat flexible, especially for time and place phrases.

For example, these are all possible:

• Di minimarket dekat kos, adik perempuan saya mencari yogurt dan biskuit untuk sarapan besok.
• Adik perempuan saya mencari yogurt dan biskuit di minimarket dekat kos untuk sarapan besok.
• Besok, adik perempuan saya mencari yogurt dan biskuit untuk sarapan di minimarket dekat kos.

But changing the order can slightly change what is being emphasized.

In your original sentence, the speaker first sets the location: At the minimarket near the boarding house...