Formulir ini masih kosong, jadi tolong isi dulu.

In Indonesian, demonstratives like ini and itu usually come after the noun they describe.

So:

• formulir ini = this form
• formulir itu = that form

This is the normal pattern:

• buku ini = this book
• rumah itu = that house

Ini formulir can exist, but it usually means something more like This is a form, not this form.

Masih means still, and kosong means empty or blank.

So masih kosong means still blank or still empty.

For a form, kosong means it has not been filled in yet. It is a very natural way to describe an uncompleted form.

Yes. Very naturally.

In Indonesian, kosong is used not only for physically empty things, but also for things with no writing or no content yet, such as:

• halaman kosong = a blank page
• kolom kosong = an empty field / blank box
• formulir kosong = a blank form

So formulir ini masih kosong sounds normal.

Good question. Jadi has more than one use.

Here, jadi means so, therefore, or thus. It connects the two parts of the sentence:

• Formulir ini masih kosong = This form is still blank
• jadi = so
• tolong isi dulu = please fill it in first

So in this sentence, jadi is a conjunction, not the verb to become.

Tolong is a common way to make a polite request. Here it is basically functioning like please.

So:

• tolong isi dulu = please fill it in first

It often comes before a verb:

• tolong buka pintunya = please open the door
• tolong tunggu = please wait

It is polite, natural, and very common in everyday Indonesian.

Because this is a request/command.

In Indonesian, the verb in an imperative is often just the base form:

• isi = fill
• buka = open
• tunggu = wait

So:

• Tolong isi dulu = Please fill it in first

If you were making a normal statement, you would often use mengisi:

• Saya mengisi formulir itu = I filled in that form / I am filling in that form

So:

• isi = imperative/request form here
• mengisi = active verb in a regular statement

Isi can be both a verb and a noun.

As a verb, it means to fill or to fill in:

• isi formulir = fill in a form

As a noun, it means contents:

• isi buku = the contents of a book

In your sentence, isi is clearly the verb.

The object is understood from context: the form.

Indonesian often leaves out words that are already obvious. Since the sentence has just mentioned formulir ini, the speaker does not need to repeat it.

So:

• Formulir ini masih kosong, jadi tolong isi dulu. = This form is still blank, so please fill it in first.

You could also say:

• Formulir ini masih kosong, jadi tolong isi formulir ini dulu.

But that sounds more repetitive.

Yes, dulu can mean formerly / in the past, but that is not what it means here.

In this sentence, dulu means something like:

• first
• before anything else
• for now

So tolong isi dulu means please fill it in first.

This use of dulu is very common in everyday Indonesian:

• Makan dulu = Eat first
• Tunggu dulu = Wait a moment / wait first
• Saya cek dulu = I’ll check first

It can also make a request sound a little softer and more natural.

Yes, the nuance is a little different.

• masih kosong focuses on the state: it is still blank
• belum diisi focuses on the action not yet done: it has not been filled in yet

So these are both natural:

• Formulir ini masih kosong.
• Formulir ini belum diisi.

They are close in meaning, but not exactly identical. In your sentence, masih kosong emphasizes the current condition of the form.

Yes. A more formal version might be:

• Formulir ini masih kosong, jadi mohon diisi dulu.

Differences:

• mohon is more formal than tolong
• diisi gives it a more formal, less direct feel

Your original sentence is polite and natural in everyday use. The more formal version would fit offices, official notices, or customer service situations better.