Renovasi dimulai hari Senin.

Because dimulai is a passive form.

• mulai = to start / begin
• memulai = to start something (active: someone starts it)
• dimulai = to be started / to begin (passive)

So Renovasi dimulai hari Senin means the renovation is started / begins on Monday, without focusing on who starts it.

Compare:

• Mereka memulai renovasi hari Senin. = They start the renovation on Monday.
• Renovasi dimulai hari Senin. = The renovation is started / begins on Monday.

Indonesian often uses this passive style when the doer is unknown, unimportant, or obvious from context.

The sentence does not say.

That is one reason the passive form dimulai is used. The focus is on the renovation, not on the person or company doing it.

If you wanted to name the doer, you could say something like:

• Kontraktor memulai renovasi hari Senin. = The contractor starts the renovation on Monday.

But in the original sentence, the agent is simply left out.

Yes. Here renovasi is a noun, meaning renovation.

So the structure is roughly:

• Renovasi = the renovation
• dimulai = begins / is started
• hari Senin = on Monday

Also, renovasi is a loanword, so it looks similar to the English word renovation.

Because Indonesian does not use articles like a, an, and the the way English does.

So renovasi can mean:

• renovation
• a renovation
• the renovation

The exact meaning depends on context.

In this sentence, English naturally translates it as the renovation because the speaker is probably talking about a specific renovation already known in context.

Indonesian often does not need a preposition like on before days of the week.

So:

• hari Senin = Monday / on Monday

This is very normal Indonesian.

You may also hear:

• pada hari Senin = on Monday

That version is a bit more explicit or formal. In everyday speech, dropping pada is very common.

Yes, absolutely.

You can say:

• Renovasi dimulai Senin.
• Renovasi dimulai hari Senin.
• Renovasi dimulai pada hari Senin.

All can mean The renovation begins on Monday.

The differences are mostly about style:

• Senin = very natural, concise
• hari Senin = also natural, slightly fuller
• pada hari Senin = more formal

Indonesian verbs do not change form for tense the way English verbs do.

So dimulai by itself does not tell you whether the action is past, present, or future. Time is usually understood from:

• context
• time words

In this sentence, hari Senin gives the time reference, but whether that Monday is in the past or future depends on the situation.

For example:

• If you are talking about next week, it means will begin on Monday.
• If you are talking about what happened last week, it means began on Monday.

This is very normal in Indonesian.

In this sentence, begins is usually the most natural English translation.

Literally, dimulai is a passive form, so it can correspond to is started. But in English, we usually say:

• The renovation begins Monday.
• The renovation starts Monday.

rather than:

• The renovation is started Monday.

So grammatically, the Indonesian is passive in form, but the most natural English translation is often an active-sounding sentence like begins or starts.

A simple way to see it is:

• Renovasi = subject
• dimulai = verb
• hari Senin = time expression

So the pattern is:

Subject + Verb + Time

This is a very common Indonesian sentence order.

Yes, sometimes, but Renovasi dimulai hari Senin is the most straightforward order.

You might also see:

• Hari Senin, renovasi dimulai.

This puts the time first for emphasis: On Monday, the renovation begins.

Indonesian allows some flexibility, especially with time expressions, but the original word order is very natural and neutral.

Because Senin is the name of a day of the week, so it is capitalized.

• hari = day (common noun, not capitalized here)
• Senin = Monday (day name, capitalized)

So:

• hari Senin = Monday

This is similar to English, where Monday is capitalized.

It is built from:

• mulai = start / begin
• prefix di- = a common passive marker

So:

• mulai → dimulai

This di- prefix often shows that something is done to the subject, or that the event is presented in a passive way.

Some similar examples:

• dibuka = opened / is opened
• ditutup = closed / is closed
• dimulai = started / is started

Yes, you may hear that, especially in casual usage, but Renovasi dimulai hari Senin is clearer and more standard.

The version with dimulai clearly expresses begins / is started.

Without di-, mulai can still appear in everyday Indonesian, but for learners, dimulai is the safer and more standard choice in this sentence.

So if you want a solid model sentence, use:

• Renovasi dimulai hari Senin.