Kitabu kiko mezani, na ninakitaka sasa.

Because kitabu belongs to the ki-/vi- noun class in Swahili.

• kitabu = book
• Its singular agreement prefix is ki-
• -ko is a locative/existence form meaning something like is there / is located

So kiko means it is there or it is located, and it agrees with kitabu.

This kind of agreement is very important in Swahili. The form of the verb often changes to match the noun class of the subject.

Ni is often used for simple identification, like:

• Hiki ni kitabu = This is a book

But in your sentence, the idea is about location: the book is on the table. For location, Swahili commonly uses forms like yuko, uko, iko, kiko, etc., depending on the noun class.

So:

• Kitabu ni mezani would sound unnatural here
• Kitabu kiko mezani is the normal way to say The book is on the table

Meza means table.
When you add -ni, it becomes a locative form:

• meza = table
• mezani = on the table / at the table / in the table area

The suffix -ni is very common in Swahili for location.

Examples:

• nyumbani = at home
• shuleni = at school
• mezani = on/at the table

Exactly how it translates in English depends on context. Here, mezani means on the table.

Here na means and. It connects the two clauses:

• Kitabu kiko mezani = The book is on the table
• na ninakitaka sasa = and I want it now

So na is just the normal conjunction joining the two ideas.

Be careful: na can also mean with in other contexts, so learners often notice it has more than one use.

Ninakitaka can be broken into parts:

• ni- = I
• -na- = present tense
• -ki- = it (object marker for a ki-/vi- noun like kitabu)
• -tak- = want
• -a = final vowel

So:

ni-na-ki-tak-a
= I am wanting it / I want it

This is a very common Swahili verb structure: subject + tense + object + verb root + final vowel

That ki is the object marker referring back to kitabu.

Since kitabu is in the ki-/vi- noun class, the object marker is also -ki-.

So instead of repeating kitabu, Swahili uses the object marker:

• ninakitaka = I want it
• where it = kitabu

This is one of the biggest differences from English: Swahili often puts object information inside the verb.

Yes. Ninataka kitabu means I want the book / I want a book, depending on context.

The difference is:

• ninataka kitabu = mentions the noun directly
• ninakitaka = says I want it, referring to a known kitabu

In your sentence, since kitabu has already been mentioned, ninakitaka is very natural.

Because Swahili usually expresses that kind of it with an object marker inside the verb, not as a separate standalone word like English does.

So English says:

• I want it

But Swahili often says the equivalent of:

• I-it-want

That is exactly what happens in ninakitaka.

Sasa means now.

It adds the idea of immediacy:

• ninakitaka = I want it
• ninakitaka sasa = I want it now

It comes after the verb here, which is very normal in Swahili.

Yes, very normal.

The sentence follows a common pattern:

• Kitabu = subject
• kiko mezani = is on the table
• na = and
• ninakitaka sasa = I want it now

So the order is basically:

Subject + verb phrase + and + subject/verb phrase

Swahili word order is often similar to English on the surface, but the big difference is that Swahili packs a lot of grammar into prefixes on the verb.

Because Swahili uses noun-class agreement in many places.

Since kitabu is a ki-/vi- noun:

• ki- appears in kiko to agree with the subject
• -ki- appears in ninakitaka to refer to the same noun as the object

So the sentence is very consistent grammatically: the noun class of kitabu controls agreement in more than one part of the sentence.

This agreement system is one of the central features of Swahili grammar.

Kitabu is singular.

Its plural is vitabu.

This follows the ki-/vi- noun class pattern:

• kitabu = book
• vitabu = books

If the subject were plural, the agreement would also change. For example, the form matching vitabu would use vi- instead of ki-.

You would change the noun and the agreement markers:

• Kitabu kiko mezani, na ninakitaka sasa.
• Vitabu viko mezani, na ninavitaka sasa.

Changes:

• kitabu → vitabu
• kiko → viko
• ninakitaka → ninavitaka

That shows how important noun-class agreement is in Swahili.