Saya memasukkan flashdisk ke dalam tas saya sebelum berangkat ke kantor.

Masuk usually means to enter or to go in by itself.

• Saya masuk ke kantor = I go into the office
• Flashdisk itu masuk ke tas = The flash drive goes into the bag

Memasukkan means to put something into something or to insert something. It is a transitive verb, so it takes an object.

• Saya memasukkan flashdisk ke dalam tas = I put the flash drive into the bag

So in this sentence, the speaker is doing the action to the flash drive, which is why memasukkan is used.

This pattern often makes a verb mean to cause something to happen or to put/apply something somewhere.

Here is the basic idea:

• masuk = enter, go in
• memasukkan = cause to enter, put into, insert

So memasukkan flashdisk ke dalam tas literally feels like cause the flash drive to go into the bag.

This is a very common pattern in Indonesian, and it often creates a verb that needs an object.

Ke dalam is more specific than just ke.

• ke = to, toward
• dalam = inside

So ke dalam tas means into the bag / to the inside of the bag, not just toward the bag.

In everyday Indonesian, people often shorten this:

• Saya memasukkan flashdisk ke tas saya
  This is also very natural and common.

Using ke dalam just makes the idea of inside clearer.

Yes. A very common shorter version is:

• Saya memasukkan flashdisk ke tas saya sebelum berangkat ke kantor.

This is natural in everyday speech.
The fuller version ke dalam tas saya sounds a bit more explicit or careful.

Both are correct.

The first saya is the subject:

• Saya = I

The second saya shows possession:

• tas saya = my bag

So the sentence structure is:

• Saya = I
• tas saya = my bag

Indonesian often repeats pronouns where English uses different forms like I and my.

Yes, definitely.

• tas saya = my bag
• tasku = my bag

Both are correct. The difference is mostly style and register:

• tas saya sounds neutral and common
• tasku can sound a bit more personal, literary, or compact

In everyday conversation, tas saya is often more common, especially in careful or standard speech.

Because in Indonesian, the subject is often omitted when it is already understood from context.

In this sentence:

• Saya memasukkan flashdisk ke dalam tas saya sebelum berangkat ke kantor.

The understood subject of berangkat is the same saya from earlier. So it means:

• before I left for the office
• literally: before leaving for the office

A more explicit version would be:

• ... sebelum saya berangkat ke kantor

That is also correct, but not necessary here.

Berangkat usually means to depart, to leave, or to set off.

So:

• berangkat ke kantor = leave for the office / set off for work

It does not focus on arriving there. It focuses on the act of leaving.

That is why sebelum berangkat ke kantor means before leaving for the office, not before going into the office.

Indonesian does not use articles like a or the the way English does.

So:

• ke kantor can mean to the office or to an office, depending on context

In this sentence, the context makes it clear that it means to the office or more naturally to work.

You only add something like kantor saya if you specifically want to say my office.

Yes, flashdisk is a very common Indonesian borrowing, especially in everyday usage. It refers to a USB flash drive.

Even though English speakers may say USB drive, thumb drive, or flash drive, Indonesian speakers commonly say flashdisk.

So this sentence sounds natural.

Sebelum means before.

It introduces a time relationship:

• Saya memasukkan flashdisk ke dalam tas saya sebelum berangkat ke kantor.
• I put the flash drive into my bag before leaving for the office.

So the action of putting the flash drive into the bag happened earlier than the action of leaving for the office.

The sentence follows a very common Indonesian order:

Subject + Verb + Object + Place/Direction + Time clause

Breaking it down:

• Saya = subject
• memasukkan = verb
• flashdisk = object
• ke dalam tas saya = direction/place
• sebelum berangkat ke kantor = time clause

So the structure is very straightforward and similar to English in many ways.

Yes, grammatically memasukkan can mean insert, put in, or place into.

But in normal English, put the flash drive into my bag sounds more natural than inserted the flash drive into my bag.

So:

• literal-ish: I inserted the flash drive into my bag before leaving for the office
• natural English: I put the flash drive into my bag before leaving for the office

Yes. Indonesian allows that very naturally:

• Sebelum berangkat ke kantor, saya memasukkan flashdisk ke dalam tas saya.

This means the same thing.
Putting the time phrase first gives it a little more emphasis, much like in English.

It sounds normal and standard. It works well in both careful everyday speech and writing.

A slightly more casual everyday version might be:

• Saya masukin flashdisk ke tas saya sebelum berangkat ke kantor.

But that is informal, because masukin is a colloquial form of memasukkan.

So the original sentence is a good standard model for learners.