Kitabu nilichokisoma jana usiku ni kizuri.

A useful rough breakdown is:

• Kitabu = book
• nilichokisoma = that I read it / that I read
• jana usiku = last night
• ni kizuri = is good / is nice

So the overall pattern is:

[noun] + [relative clause] + [main statement]

That gives: The book that I read last night is good.

It can be split like this:

• ni- = I
• -li- = past tense
• -cho- = relative marker agreeing with kitabu
• -ki- = object marker agreeing with kitabu
• som- = read
• -a = final vowel

So nilichokisoma literally contains something like I-past-which-it-read. In natural English, that becomes that I read.

Because they do two different jobs.

• -cho- marks the verb as a relative clause and agrees with kitabu
• -ki- marks kitabu as the object of read

So both pieces point back to kitabu, but they are not duplicates. One means which/that, and the other means it.

In Swahili, relative meanings are often built directly into the verb instead of using a separate word like English that or which.

So English says:

• the book that I read

But Swahili can say:

• kitabu nilichokisoma

The idea of that/which is carried by the relative marker -cho- inside the verb.

Yes. A more analytic version is:

Kitabu ambacho nilikisoma jana usiku ni kizuri.

Here, ambacho works a bit more like an overt relative word such as which/that. Both patterns are useful to know:

• kitabu nilichokisoma
• kitabu ambacho nilikisoma

The first packs the relative meaning into the verb; the second uses ambacho more explicitly.

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

Kitabu belongs to noun class 7, so the adjective stem -zuri takes the class 7 agreement prefix ki-:

• ki- + -zuri = kizuri

So kizuri means good/nice/beautiful in a form that matches kitabu.

Kitabu is in class 7 singular. Its plural is vitabu, in class 8.

That matters because several other parts of the sentence must agree with it:

• relative marker: -cho-
• object marker: -ki-
• adjective agreement: ki- in kizuri

Swahili grammar relies heavily on this kind of agreement, so learning noun classes is very important.

Here ni is the copula, the word linking the subject to its description:

• Kitabu ... ni kizuri = The book ... is good

It is often translated as is, but it does not behave exactly like English be in every situation. In this sentence, though, is is the right translation.

This is an important distinction:

• kitabu kizuri = a good book / good book
  
  • this is a noun phrase
• kitabu ni kizuri = the book is good
  
  • this is a full sentence

So ni turns it into a statement.

Because the sentence contains two different ideas:

1. I read the book last night — this is the past event, so it uses -li-
2. The book is good — this is the main statement, and it is present, so we get ni kizuri

So the reading happened in the past, but the judgment about the book is being made now.

Jana means yesterday, and usiku means night. Together, jana usiku is the normal way to say last night.

So it refers to the time when the reading happened, not the time when the book is good.

Swahili commonly puts the noun first and then follows it with the relative clause:

• kitabu nilichokisoma = the book that I read

After that comes the main statement:

• ni kizuri = is good

So the structure is very natural in Swahili: [the book that I read last night] [is good]

Swahili does not have articles like English a and the.

That means kitabu can mean:

• a book
• the book

The context tells you which English article is best. In this sentence, English usually says the book because the relative clause identifies a specific one: the book that I read last night.

The adjective stem -zuri can cover several related meanings, including:

• good
• nice
• beautiful

The best translation depends on context. For a book, good or nice is usually the most natural choice.

It would become:

Vitabu nilivyovisoma jana usiku ni vizuri.

Here the agreements change to match vitabu:

• vitabu = books
• -vyo- = relative marker for class 8
• -vi- = object marker for class 8
• vizuri = good/nice, agreeing with class 8

So it means The books that I read last night are good.