Dia sudah pergi sebelum saya tiba.

Dia can mean either he or she. Malay third-person singular pronouns do not normally mark gender, so you understand it from context.

So:

• Dia sudah pergi = He has already left or She has already left

If the wider conversation makes the person clear, Malay usually does not need anything more specific.

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

So:

• pergi stays pergi
• tiba stays tiba

Time is usually shown by:

• time words
• context
• aspect markers like sudah

In this sentence, the past meaning comes from the whole sentence, especially sudah and the sequence created by sebelum.

Sudah means already, and very often it also shows that an action is completed.

So dia sudah pergi gives the sense of:

• he/she already went
• he/she has already left
• in this full sentence, effectively he/she had already left

It helps show that the leaving happened before the other event.

Malay does not have a direct equivalent of the English past perfect in the same way English does.

Instead, Malay expresses the same idea through:

• sudah for completion
• sebelum for the earlier/later relationship between the two actions

So Dia sudah pergi sebelum saya tiba naturally conveys:

• the leaving happened first
• the arriving happened later

That is why English often uses had left.

Yes: Dia pergi sebelum saya tiba is still grammatical.

But the nuance changes slightly:

• Dia pergi sebelum saya tiba = He/She left before I arrived
• Dia sudah pergi sebelum saya tiba = He/She had already left before I arrived

With sudah, the sentence more clearly emphasizes that the action was already completed.

It can mean both, depending on context.

In this sentence, pergi is most naturally understood as leave / go away, because the idea is that the person was gone before I arrived.

So:

• Dia sudah pergi often means He/She has already left

Malay often uses one verb where English might choose between two different verbs.

Sebelum means before.

It introduces the time clause:

• sebelum saya tiba = before I arrived

So the sentence structure is:

• Dia sudah pergi = main clause
• sebelum saya tiba = time clause

This shows the order of events:

1. the person left
2. I arrived later

Both tiba and sampai can relate to arriving, but they are not always identical in tone or usage.

• tiba = arrive
• sampai = arrive / reach / get to

In many contexts, both can work:

• sebelum saya tiba
• sebelum saya sampai

Tiba often sounds a bit more formal or standard in writing.
Sampai is very common in everyday speech.

So this sentence uses a perfectly natural, slightly more standard choice.

Yes. You can put the before clause first:

• Sebelum saya tiba, dia sudah pergi.

This means the same thing as:

• Dia sudah pergi sebelum saya tiba.

Both are natural. The choice depends on what you want to emphasize first.

No. Saya is a polite and neutral way to say I.

Depending on the situation, other pronouns are possible, such as:

• aku = more informal, casual, personal
• sometimes the speaker might even use their name in certain contexts

So in very casual speech, you might hear:

• Dia sudah pergi sebelum aku tiba.

But saya is the safest general choice for learners.

Yes.

• Dia sudah pergi. = He/She has already left.

That is a complete sentence on its own.
The part sebelum saya tiba simply adds extra information about when that happened.

Yes, it is natural and correct.

It is a clear standard sentence with:

• a subject: dia
• an aspect marker: sudah
• a verb: pergi
• a time clause: sebelum saya tiba

It is a good example of how Malay expresses a sequence of past events without changing verb forms.