Mwanafunzi aliyekuja mapema alikuwa na kitabu.

Aliyekuja means who came.

It is made of several parts:

• a- = subject marker for a singular person/noun in class 1
• -li- = past tense
• -ye- = relative marker for class 1, here meaning who
• -kuja = verb root come

So a-li-ye-kuja literally works like the one who came.

In Swahili, a relative clause usually comes after the noun it describes.

So:

• mwanafunzi = student
• aliyekuja mapema = who came early

Together: mwanafunzi aliyekuja mapema = the student who came early.

This is normal Swahili word order.

Because they both agree with mwanafunzi, which is a singular person noun.

In Swahili, verbs must agree with the noun class of their subject.
Mwanafunzi is singular, so the verb uses a-.

That is why you get:

• a-li-ye-kuja
• a-li-kuwa

If it were plural wanafunzi, you would use wa- instead.

No. A- does not mean specifically he.

In this sentence, a- simply shows agreement with a singular human noun. It can refer to:

• he
• she
• sometimes even they in English if the gender is unknown

So mwanafunzi is gender-neutral unless context tells you more.

Mapema means early.

It is an adverb modifying kuja (to come), so:

• aliyekuja mapema = who came early

It tells you how/when the student came.

No. Here na does not mean and.

In alikuwa na kitabu, na means with, and the whole expression kuwa na is the normal way to express have.

So:

• alikuwa na kitabu = he/she had a book

Even though na can also mean and in other sentences, that is not its role here.

Swahili often expresses possession with kuwa na, literally something like to be with.

So instead of one simple verb like English have, Swahili commonly uses this pattern:

• ana kitabu = he/she has a book
• alikuwa na kitabu = he/she had a book

In this sentence, alikuwa na is the past form used to show possession in the past.

You know from context, not from a separate word.

Swahili has no articles like a or the.
So mwanafunzi can mean:

• a student
• the student

Likewise kitabu can mean:

• a book
• the book

The situation or previous conversation tells you which one is meant.

Because Swahili usually writes verb elements together as a single word.

Subject markers, tense markers, relative markers, and the verb root are normally attached:

• a-li-ye-kuja

So what looks like several ideas in English becomes one written verb form in Swahili.

Yes. That is also correct.

Both of these can mean the student who came early:

• mwanafunzi aliyekuja mapema
• mwanafunzi ambaye alikuja mapema

The version with aliyekuja is more compact because the relative meaning is built directly into the verb.
The ambaye version is a little more separate and may feel easier to beginners.

You would change the nouns and the agreements:

Wanafunzi waliokuja mapema walikuwa na vitabu.

Changes:

• mwanafunzi → wanafunzi = student → students
• aliyekuja → waliokuja = who came
• alikuwa → walikuwa = they were / they had
• kitabu → vitabu = book → books

So the sentence becomes The students who came early had books.