Kalau mouse komputer saya tertinggal di kantor, saya tidak bisa ikut rapat daring dari rumah.

Here kalau means if:

• Kalau mouse komputer saya tertinggal di kantor ... = If my computer mouse is left behind at the office ...

In everyday Indonesian, kalau is a very common way to introduce a condition. It can sometimes also feel like when depending on context, but in this sentence it clearly means a condition: if that happens, then...

Other possible words:

• jika = also if, but more formal
• bila = also if, somewhat formal/literary

So kalau is the most natural conversational choice here.

Tertinggal means something like left behind or accidentally left somewhere.

So:

• mouse komputer saya tertinggal di kantor
  = my computer mouse got left behind at the office

This is different from actively leaving something somewhere on purpose.

A useful comparison:

• Saya meninggalkan mouse komputer saya di kantor.
  = I left my computer mouse at the office.
  This focuses on the action of leaving it there.

• Mouse komputer saya tertinggal di kantor.
  = My computer mouse was left behind at the office.
  This focuses on the result/situation, often with the sense that it happened unintentionally.

So tertinggal often suggests oops, I forgot it there.

Indonesian noun phrases are usually built with the main noun first, then modifiers after it.

So:

• mouse = the main noun
• komputer = describes what kind of mouse
• saya = my

That gives:

• mouse komputer saya = my computer mouse

This follows a common Indonesian pattern:

• buku saya = my book
• rumah besar = big house
• rapat daring = online meeting

So the order is generally:

noun + modifier + possessor

In this case:

mouse + komputer + saya

Because the two saya do different jobs:

1. mouse komputer saya
   Here saya means my and shows possession.

2. saya tidak bisa ikut ...
   Here saya means I and is the subject of the main clause.

So the sentence literally works like:

• If my computer mouse is left at the office, I can't join the online meeting from home.

Repeating saya is completely normal in Indonesian. It does not sound unnatural.

Ikut means join, take part, or come along.

So:

• ikut rapat = join the meeting / take part in the meeting

This is very natural, especially in everyday speech and especially for online meetings.

A few alternatives:

• menghadiri rapat = attend the meeting
  More formal, often used in more official contexts

• bergabung dalam rapat = join the meeting
  Also possible, but a bit less casual

In this sentence, ikut rapat daring sounds very natural and conversational.

Rapat daring means online meeting.

• rapat = meeting
• daring = online

Daring comes from dalam jaringan, literally in the network. It is an official Indonesian term for online.

In real life, people also often say:

• rapat online
• meeting online

So all of these are possible, but they differ in style:

• rapat daring = more standard/Indonesian
• rapat online = very common in everyday use
• meeting online = informal, with English influence

This is a very important distinction:

• di = in / at / on → location
• dari = from → origin or starting point

So:

• tertinggal di kantor = left behind at the office
  This tells you the location of the mouse.

• ikut rapat daring dari rumah = join the online meeting from home
  This tells you where the speaker is joining from.

So the sentence contrasts two places:

• the mouse is at the office
• the speaker wants to join the meeting from home

Tidak bisa usually means cannot in the sense of not able to.

So here:

• saya tidak bisa ikut rapat daring dari rumah
  = I can’t join the online meeting from home

In this sentence, it means I’m unable to, not I’m not allowed to.

A few related expressions:

• tidak bisa = cannot / not able to
• nggak bisa = same meaning, more informal
• tidak dapat = can also mean cannot, often a bit more formal or written

Because the problem is practical—the mouse was left at the office—tidak bisa is the natural choice.

Yes. Mouse is very commonly used in Indonesian for the computer device.

So mouse komputer is normal and easy to understand.

There is also a more purely Indonesian term:

• tetikus = mouse

But tetikus is much less common in everyday speech. Most people simply say mouse.

So these are possible:

• mouse komputer saya = very common
• tetikus komputer saya = correct, but less common

Yes, it can be reordered.

The original sentence:

• Kalau mouse komputer saya tertinggal di kantor, saya tidak bisa ikut rapat daring dari rumah.

You can also say:

• Saya tidak bisa ikut rapat daring dari rumah kalau mouse komputer saya tertinggal di kantor.

Both are grammatical.

The difference is mainly in focus:

• Kalau ... , saya tidak bisa ...
  starts with the condition, so it highlights the if part first

• Saya tidak bisa ... kalau ...
  starts with the result, so it highlights I can’t join first

In writing, a comma is commonly used when the kalau clause comes first.

It is mostly neutral everyday Indonesian.

Parts that feel neutral:

• kalau
• saya
• tidak bisa
• ikut

One slightly more formal/standard part is:

• rapat daring

In casual speech, many people might say something like:

• Kalau mouse komputer saya ketinggalan di kantor, saya nggak bisa ikut meeting online dari rumah.

That version is more informal because of:

• ketinggalan instead of tertinggal
• nggak instead of tidak
• meeting online instead of rapat daring

So your original sentence is natural, clear, and fairly standard.