Saya membeli buku catatan dan pulpen di toko kampus sebelum kuliah dimulai.

Beli is the root word meaning to buy.
Membeli is the active verb form made with the meN- prefix.

In neutral or formal Indonesian, membeli is the standard form when the verb has a direct object, as it does here:

• Saya membeli buku catatan dan pulpen. = I bought a notebook and a pen.

In casual speech, people often say:

• Saya beli buku catatan dan pulpen.

That sounds more conversational, but both are correct.

Indonesian usually does not use articles the way English does. So nouns often appear by themselves:

• buku catatan can mean a notebook, the notebook, or just notebook(s) depending on context.
• pulpen can mean a pen, the pen, or pen(s).

If you need to be more specific, Indonesian can add other words, such as:

• sebuah buku catatan = a notebook
• buku catatan itu = that/the notebook
• buku catatan ini = this notebook

But in many everyday sentences, nothing extra is needed.

In Indonesian, the main noun usually comes first, and the word that describes it comes after.

So:

• buku catatan = literally book notebook/for notes → notebook

Here, buku is the main noun, and catatan describes its function.

If you said catatan buku, it would sound more like:

• notes about a book
• book notes

So the order matters a lot.

Yes, pulpen is very common in everyday Indonesian and is a perfectly normal word for pen.

You can also say pena, which is also understood. Very roughly:

• pulpen = common in daily speech
• pena = also correct, sometimes a bit more standard or formal

In ordinary conversation, many Indonesians would naturally say pulpen.

Here, di is a preposition meaning in, at, or sometimes on, depending on context.

So:

• di toko kampus = at the campus store

It tells you the location where the action happened.

This is a very important spelling point in Indonesian.

There are two different di's:

1. di as a preposition = at/in/on

   • written separately
   • example: di toko = at the store

2. di- as a verb prefix for the passive

   • written attached
   • example: dimulai = started / is begun

So:

• di toko ✅
• dimulai ✅
• ditoko ❌
• di mulai ❌

A useful rule:
If di shows a place, write it separately.
If di- is part of a verb, write it together.

Because di shows location, while ke shows direction or movement toward a place.

Compare:

• Saya membeli buku di toko kampus. = I bought books at the campus store.
• Saya pergi ke toko kampus. = I went to the campus store.

In your sentence, the buying happened at that location, so di is the correct choice.

Yes, that is the general idea.

Indonesian often puts two nouns together, with the main noun first:

• toko kampus = campus store / store on campus

So toko is the main noun, and kampus modifies it.

Indonesian usually does this without using:

• of
• apostrophe 's

Other similar patterns are:

• rumah sakit = hospital
• kartu kredit = credit card
• buku sejarah = history book

Kuliah can have several related meanings, including:

• college/university study
• a lecture
• a university class

In this sentence, because it is followed by dimulai (started/began), it most naturally refers to class or the lecture beginning.

So sebelum kuliah dimulai means something like:

• before class started
• before the lecture began

Dimulai is the passive form related to memulai (to start something).

So:

• memulai = to start something
• dimulai = to be started / to begin

In the sentence:

• sebelum kuliah dimulai

the focus is on the class beginning, not on who started it.

A very literal breakdown is:

• before the class was started

But in natural English, that usually becomes:

• before class began
• before class started

Yes. That is also possible, especially in more casual speech.

Compare:

• sebelum kuliah dimulai = a bit more formal or structured
• sebelum kuliah mulai = more conversational

Both can mean before class starts/started.

No. Indonesian verbs generally do not change form for tense the way English verbs do.

So membeli does not automatically mean:

• bought
• buy
• will buy

The time comes from context or from time words such as:

• kemarin = yesterday
• tadi = earlier
• sekarang = now
• besok = tomorrow

So if this sentence is translated as I bought..., that comes from context, not from the verb form alone.

Yes, it can be omitted if the subject is already clear from context, especially in conversation.

For example, someone might simply say:

• Membeli buku catatan dan pulpen di toko kampus sebelum kuliah dimulai.

However, in a complete standalone sentence, especially in writing, saya makes the sentence clearer and more natural.

Indonesian often leaves number unspecified unless it matters.

So this phrase could refer to:

• a notebook and a pen
• or, in a broader context, notebooks and pens

If you want to be specific, Indonesian can add numbers or quantity words:

• sebuah buku catatan dan sebuah pulpen = a notebook and a pen
• dua buku catatan dan tiga pulpen = two notebooks and three pens
• beberapa buku catatan = several notebooks

Without those markers, the exact number is often understood from context.

Yes, absolutely.

You can say:

• Sebelum kuliah dimulai, saya membeli buku catatan dan pulpen di toko kampus.

This is very natural and just changes the emphasis slightly. Putting the time phrase first highlights when the action happened, much like in English:

• Before class started, I bought a notebook and a pen at the campus store.