Kitabu hiki ni nzuri kabisa.

Not quite in standard Swahili.

Most teachers and grammars would expect:

Kitabu hiki ni kizuri kabisa.

Why? Because kitabu belongs to the ki-/vi- noun class, and the adjective must agree with it.

• kitabu = book
• hiki = this, matching kitabu
• kizuri = good/nice, also matching kitabu

The form nzuri belongs to a different agreement pattern, so it does not match kitabu here.

So the sentence is best corrected to:

Kitabu hiki ni kizuri kabisa.

Because hiki must agree with kitabu.

Swahili uses noun classes, and words like demonstratives such as this and that change form to match the noun class.

Since kitabu is in the ki-/vi- class, the correct form for this is:

• hiki = this

Compare:

• kitabu hiki = this book
• vitabu hivi = these books

If the noun were in a different class, the demonstrative would change too. So hii would be used with different kinds of nouns, not with kitabu.

Ni is the copula here, meaning something like is, am, or are.

So in:

Kitabu hiki ni kizuri kabisa

ni links the subject kitabu hiki with the description kizuri kabisa.

A simple way to think of it is:

• X ni Y = X is Y

Unlike English, ni does not change for person or number:

• Mimi ni... = I am...
• Yeye ni... = he/she is...
• Vitabu hivi ni... = these books are...

Because adjectives in Swahili often agree with the noun class of the noun they describe.

The basic adjective stem here is:

• -zuri = good, nice, beautiful

But its full form changes depending on the noun:

• kitabu kizuri = a good book
• vitabu vizuri = good books
• nyumba nzuri = a good house
• mtoto mzuri = a good child

So with kitabu, you need:

• kizuri

This agreement happens whether the adjective is directly next to the noun or used after ni in a predicate.

Kabisa is an intensifier. It adds emphasis.

In this sentence, it means something like:

• very
• really
• absolutely
• completely, depending on context

So:

• kizuri kabisa = very good / really nice / absolutely good

In everyday use, kabisa often works like a strong very or really.

Swahili usually does not use articles like English a, an, or the.

So kitabu can mean:

• book
• a book
• the book

The exact meaning depends on context.

In your sentence, hiki makes it more specific:

• kitabu hiki = this book

So even without an article, the phrase is already definite and clear.

Kitabu is singular in the ki-/vi- noun class.

That matters because several other words in the sentence must match it:

• kitabu = book
• hiki = this, matching the ki- class
• kizuri = good, matching the ki- class

Its plural is:

• vitabu = books

Then the agreeing words also change:

• vitabu hivi ni vizuri kabisa = these books are very good

So noun class is one of the most important parts of Swahili grammar, because it affects agreement across the sentence.

You would say:

Vitabu hivi ni vizuri kabisa.

Here is what changed:

• kitabu → vitabu = book → books
• hiki → hivi = this → these
• kizuri → vizuri = good → good, matching the plural class

So the pattern is:

• Kitabu hiki ni kizuri kabisa. = This book is very good.
• Vitabu hivi ni vizuri kabisa. = These books are very good.

Yes, you may hear both, but kitabu hiki is the more neutral and basic order to learn first.

• kitabu hiki = this book

Putting the demonstrative first, as in hiki kitabu, can add emphasis, somewhat like saying this book with extra focus in English.

For a learner, the safest default is:

• noun + demonstrative
• kitabu hiki

So for everyday use, kitabu hiki ni kizuri kabisa is the best model.