hon no itibu wo yomimasita.

It is read:

ほん の いちぶ を よみました。
Hon no ichibu o yomimashita.

A few notes:

• 本 = ほん
• 一部 = いちぶ
• を is usually pronounced o
• 読みました = よみました

の links two nouns.

Here, 本の一部 means a part of the book or part of the book.

You can think of A の B as often meaning:

• B of A
• A’s B
• B related to A

So:

• 本 = book
• 一部 = part/portion
• 本の一部 = part of the book

Here, 一部 means a part or a portion.

That is a very common meaning.
Be aware that 一部 can also mean one copy in other contexts, but not here.

For example:

• 本の一部 = part of a book
• 資料を一部ください = please give me one copy of the document

So the exact meaning depends on context.

を marks the direct object of the verb.

The verb here is 読みました (read), and the thing being read is 本の一部.

So:

• 本の一部 = the part of the book
• を = marks that as the object
• 読みました = read

In other words, 本の一部を is the thing that was read.

Because Japanese normally puts the verb at the end of the sentence.

A very common basic Japanese word order is:

topic / subject + object + verb

So in this sentence:

• 本の一部を = object
• 読みました = verb

That is completely normal Japanese sentence structure.

The dictionary form is 読む.

Here is the pattern:

• 読む = plain form / dictionary form
• 読みます = polite non-past
• 読みました = polite past

So 読みました is the polite past form of 読む.

Because 読む is a godan verb.

With godan verbs, the ending changes depending on the form.
For 読む:

• dictionary form: 読む
• ます-stem: 読み
• polite present: 読みます
• polite past: 読みました

So the む changes to み before ます.

This is a normal conjugation pattern:

• 書く → 書きます
• 話す → 話します
• 読む → 読みます

Yes, the subject is omitted.

Japanese often leaves out the subject when it is obvious from context.

So 本の一部を読みました。 could mean:

• I read part of the book.
• He read part of the book.
• She read part of the book.
• We read part of the book.

The listener usually understands who did it from the situation.

Japanese does not use articles the way English does.

There is no direct equivalent of a/an and the that must appear in sentences like this.

So 本, 一部, and 本の一部 do not automatically tell you whether English should use:

• a
• the
• sometimes some

That detail is usually understood from context.

No. Standard Japanese normally does not use spaces between words.

So this would usually be written as:

本の一部を読みました。

Spaces are often added in textbooks or beginner materials to make the structure easier to see.

It is much more natural to say 本の一部を読みました when you mean I read part of the book.

Why?

Because 本の一部 is treated as one noun phrase: part of the book.
That whole phrase becomes the object of 読む.

So:

• natural: 本の一部を読みました
• less natural for this meaning: 本を一部読みました

If you want to say I read some of the book, another natural option is:

• 本を少し読みました。

But for part of the book, 本の一部を読みました is the cleanest form.

Both can mean part of the book.

But:

• 一部 is very common and natural
• 一部分 is also correct, but can feel a bit more explicit or slightly more formal depending on context

In everyday use, 本の一部 is perfectly natural.