Saya pergi ke supermarket sekali seminggu untuk membeli sayur segar.

Yes. Saya and aku both mean I, but they differ in tone.

• saya = more neutral, polite, and widely usable
• aku = more informal and personal

So:

• Saya pergi ke supermarket sekali seminggu... sounds neutral and safe in most situations.
• Aku pergi ke supermarket sekali seminggu... sounds more casual, like everyday speech with friends or family.

For learners, saya is often the safest choice.

Ke is a preposition meaning to when talking about movement toward a place.

So:

• pergi = to go
• ke supermarket = to the supermarket

Together, pergi ke supermarket means go to the supermarket.

Some useful comparisons:

• ke = to, toward
• di = in, at
• dari = from

Examples:

• Saya pergi ke pasar. = I go to the market.
• Saya di pasar. = I am at the market.
• Saya pulang dari pasar. = I come home from the market.

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

So supermarket can mean:

• a supermarket
• the supermarket

The exact meaning depends on context.

In this sentence, English naturally translates it as the supermarket or sometimes just the supermarket / a supermarket, depending on the situation. Indonesian usually does not need to mark that difference.

Sekali seminggu literally means once a week.

Breakdown:

• sekali = once, one time
• seminggu = a week

So:

• sekali seminggu = once per week / once a week

This is a very common way to express frequency in Indonesian.

Similar patterns:

• sekali sehari = once a day
• dua kali seminggu = twice a week
• tiga kali sebulan = three times a month

Note that kali is often used for counting occurrences:

• satu kali / sekali = once
• dua kali = twice
• tiga kali = three times

Yes, there is a small difference.

• seminggu = one week / a week
• satu minggu = one week

Both can refer to the length of one week, but se- often has the sense of one in a more set, natural expression.

In frequency expressions, seminggu is very common:

• sekali seminggu = once a week

You may also see:

• satu kali seminggu

That is understandable, but sekali seminggu sounds more natural.

The prefix se- often means one:

• sehari = one day / a day
• sebulan = one month / a month
• setahun = one year / a year

Sometimes, but the meaning is slightly different.

• sekali seminggu = once a week
• setiap minggu = every week

These are close, but not always identical.

For example:

• Saya pergi ke supermarket sekali seminggu.
  = I go to the supermarket once a week.
• Saya pergi ke supermarket setiap minggu.
  = I go to the supermarket every week.

The second version does not directly emphasize once. It only says the action happens every week. It could be once per week, but the sentence itself does not specify the number of times.

Untuk means for or in order to, and membeli means to buy / buying.

So:

• untuk membeli sayur segar = to buy fresh vegetables

Using membeli is slightly more formal and standard than beli.

Both are possible in many contexts:

• untuk membeli sayur segar = more standard/formal
• untuk beli sayur segar = more conversational

In careful written Indonesian, untuk membeli is a very natural choice.

The prefix meN- (which changes form depending on the next sound) often forms active verbs.

Here:

• beli = buy
• membeli = to buy

So membeli is the active verb form.

In many everyday situations, Indonesians also use the base form beli, especially in conversation:

• Saya mau beli sayur. = I want to buy vegetables.

But in more standard or formal grammar, membeli is often preferred after words like untuk in sentences like this.

In Indonesian, adjectives usually come after the noun.

So:

• sayur segar = fresh vegetables
• literally: vegetables fresh

This is the normal word order.

More examples:

• rumah besar = big house
• air dingin = cold water
• buah manis = sweet fruit

So sayur segar is exactly what you would expect in Indonesian grammar.

Sayur can mean vegetable or vegetables, depending on context.

Indonesian often does not mark plural explicitly when it is already clear from context.

So:

• membeli sayur segar naturally means to buy fresh vegetables

If you really want to emphasize plural, Indonesian can use reduplication:

• sayur-sayur

But in this sentence that would usually sound unnecessary. The unmarked form sayur is perfectly normal.

They are related, but not always identical in feel.

• sayur is very common in everyday speech and often means vegetables
• sayuran also means vegetables, and can sound a little more like the category or type of food

In many contexts, both work:

• membeli sayur segar
• membeli sayuran segar

The first one sounds very natural and everyday. Learners will hear sayur a lot in real conversation.

Indonesian word order is often flexible, but this placement is very natural.

The basic sentence is:

• Saya pergi ke supermarket = I go to the supermarket

Then you add frequency:

• sekali seminggu = once a week

Then purpose:

• untuk membeli sayur segar = to buy fresh vegetables

So the overall structure is:

Saya + pergi ke supermarket + sekali seminggu + untuk membeli sayur segar

This is a normal and clear order:

1. subject
2. action and destination
3. frequency
4. purpose

Other orders may also be possible in context, but this one is straightforward and natural.

In casual spoken Indonesian, people sometimes omit words when the meaning is obvious, but in a full standard sentence, pergi is better.

• Saya pergi ke supermarket sekali seminggu... = full, clear, standard
• Saya ke supermarket... = more colloquial, more like I’m going to the supermarket or I go to the supermarket, depending on context

For learners, it is best to keep pergi here.

Yes. Supermarket is a borrowed word and is commonly used in Indonesian.

Indonesian uses many loanwords, especially for modern places, technology, and international concepts. So this sentence sounds perfectly natural.

You might also hear other shopping-related words such as:

• pasar = market
• toko = shop/store
• minimarket = convenience-style small market
• swalayan = self-service store / supermarket, though this can sound more formal or specific depending on context

The sentence specifically includes sekali seminggu, so it clearly means once a week.

If the sentence were:

• Saya pergi ke supermarket setiap minggu untuk membeli sayur segar.

that would mean:

• I go to the supermarket every week to buy fresh vegetables.

That version tells you the action happens every week, but does not explicitly say it is only one time each week.

So sekali seminggu is more precise.