Kimi erken geldi, kimi geç geldi.

Here, kimi means some or some of them.

When Turkish repeats it — kimi ..., kimi ... — it creates the pattern some ..., some ....

So:

• Kimi erken geldi = Some came early
• Kimi geç geldi = Some came late

In this sentence, the people are understood from context, so Turkish does not need to say people explicitly.

It looks the same, but here it is not the question word.

Turkish kimi can be:

• kimi? = whom? / who? in the accusative
• kimi = some, some of them

In Kimi erken geldi, kimi geç geldi, it clearly means some because of the structure and context.

Because Turkish often expresses contrast or distribution by repeating a word.

So:

• kimi erken geldi, kimi geç geldi

literally works like:

• some came early, some came late

This repetition shows that one group did one thing, and another group did something else.

This is normal in Turkish with words like kimi.

Even though the meaning is plural in English (some people), Turkish often uses a singular verb after an indefinite or distributive subject like this:

• Kimi erken geldi.
• Kimi geç geldi.

This is very natural Turkish.

English learners often expect something like geldiler because the meaning involves more than one person, but Turkish does not have to match English here.

Yes, that is a very natural English translation.

A few good translations are:

• Some came early, some came late.
• Some arrived early, others arrived late.
• Some of them came early, some came late.

The exact English wording can vary, but the Turkish structure stays the same.

They are adverbs here.

• erken = early
• geç = late

They describe how / when the action happened:

• erken geldi = came early
• geç geldi = came late

So the structure is:

• kimi
  • adverb
    • verb

Because Turkish normally puts the verb at the end of the clause.

So:

• Kimi erken geldi
• Kimi geç geldi

This is standard Turkish word order.

A native English speaker may want to say something more like Kimi geldi erken, but that is not the normal neutral order.

Yes, usually there is an implied idea like:

• some people
• some of them
• some students
• some guests

The noun is omitted because it is already understood from context.

So kimi here works like a pronoun: it stands on its own without naming the group again.

Yes.

It can refer to people or things, depending on context.

For example:

• Kimi kitapları beğendi, kimi beğenmedi.
  Some liked the books, some didn’t.

• Kimi kırmızıydı, kimi maviydi.
  Some were red, some were blue.

So in your sentence, it probably refers to people, but the word itself is not limited to people.

It is fairly neutral and natural.

Kimi ..., kimi ... is a normal written and spoken pattern, though in everyday speech many speakers may also use forms like:

• Bazıları erken geldi, bazıları geç geldi.
• Kimisi erken geldi, kimisi geç geldi.

All of these are natural.
Kimi ..., kimi ... can sound a little more compact or literary than bazıları ..., bazıları ..., but it is still perfectly normal.

They are very close in meaning here.

• kimi = some
• kimisi = some of them / some

In many sentences, both are possible:

• Kimi erken geldi, kimi geç geldi.
• Kimisi erken geldi, kimisi geç geldi.

Kimisi can sound slightly fuller because of the -si ending, but both are used to divide a group into parts.

Yes.

You could also say:

• Bazıları erken geldi, bazıları geç geldi.

This means almost the same thing: Some came early, some came late.

A rough comparison:

• kimi ..., kimi ... = compact, distributive, often elegant
• bazıları ..., bazıları ... = very common, clear, everyday

The comma is very natural because the sentence has two parallel parts:

• Kimi erken geldi,
• kimi geç geldi.

It helps show the contrast between the two groups.

Without the comma, the sentence might still be understandable, but the comma is the normal written choice.

Sometimes, yes, if the meaning is very clear.

For example:

• Kimi erken, kimi geç geldi.

This is also natural and means the same thing.

But with both verbs included:

• Kimi erken geldi, kimi geç geldi.

the sentence is fuller and especially clear for learners.

Not necessarily.

It simply divides a larger group into two parts:

• one part came early
• another part came late

It does not tell you exactly who they were, how many there were, or whether the groups were equal. It just gives a general distribution.

Not in this sentence.

You may have seen expressions like:

• kimi zaman = sometimes
• kimi vakit = sometimes

But in Kimi erken geldi, kimi geç geldi, kimi does not mean sometimes. It means some / some of them. The rest of the sentence makes that clear.