Menurut saya, buku sejarah itu bagus dan mudah dimengerti.

Menurut saya literally means according to me, but in natural English it is usually translated as in my opinion or I think.

• menurut = according to
• saya = I / me

It is a common and polite way to give an opinion in Indonesian.

Other similar expressions:

• saya rasa = I think / I feel
• saya pikir = I think
• menurutku = in my opinion (more casual)

So Menurut saya, ... is a very normal way to begin a sentence when giving your view.

Because Menurut saya is an opinion phrase, not the main subject of the sentence.

The actual thing being talked about is:

• buku sejarah itu = that history book / the history book

So the structure is roughly:

• Menurut saya = in my opinion
• buku sejarah itu = the history book
• bagus dan mudah dimengerti = is good and easy to understand

Indonesian often puts an opinion phrase at the beginning, followed by the thing being described.

In this sentence, itu most literally means that, but in natural translation it can also function a bit like the, depending on context.

So buku sejarah itu can mean:

• that history book
• the history book (if both speaker and listener know which book is meant)

This is very common in Indonesian. Demonstratives like ini and itu often help identify a noun:

• buku ini = this book
• buku itu = that book / the book in question

Buku sejarah means history book: a book about history.

Here, sejarah is a noun modifying another noun:

• buku = book
• sejarah = history

So together:

• buku sejarah = history book

By contrast, bersejarah means historic or historical in importance. So:

• buku sejarah = a book about history
• buku bersejarah = a historic book

Those are different meanings.

Because Indonesian often does not use a verb equivalent to to be in simple descriptive sentences.

In English, you say:

• The book is good

In Indonesian, you can simply say:

• Buku itu bagus

No separate word for is is necessary.

This is completely normal when connecting a subject to an adjective or noun phrase.

Examples:

• Dia guru. = He/She is a teacher.
• Rumah itu besar. = That house is big.
• Buku itu bagus. = That book is good.

Bagus is an adjective meaning good, nice, excellent, or well-made, depending on context.

In this sentence, it describes the book:

• buku sejarah itu bagus = the history book is good

It is a very common everyday adjective and can be used for many things:

• film bagus = a good movie
• ide bagus = a good idea
• hasilnya bagus = the result is good

Mudah dimengerti means easy to understand.

Breakdown:

• mudah = easy
• dimengerti = understood / to be understood

Together, this forms a common Indonesian pattern:

• mudah + passive verb
• literally: easy to be understood
• natural English: easy to understand

Similar examples:

• mudah dilakukan = easy to do
• mudah ditemukan = easy to find
• mudah dipelajari = easy to learn

So mudah dimengerti is a very natural Indonesian way to say easy to understand.

This is one of the most useful grammar points in the sentence.

• mengerti = to understand
• dimengerti = understood / to be understood

In mudah dimengerti, the focus is on the book as something that can be understood. That is why Indonesian uses the di- form.

Compare:

• Saya mengerti buku itu. = I understand that book.
• Buku itu mudah dimengerti. = That book is easy to understand.

In the second sentence, the book is the thing receiving the action of understanding, so the passive-style form dimengerti is used.

They are very similar, and in many contexts either one works.

• mudah dimengerti = easy to understand
• mudah dipahami = easy to comprehend / easy to understand

A small nuance:

• mengerti often feels a bit more everyday and direct
• memahami can sound slightly more formal or deeper, like comprehend

For a book, both are very natural:

• Buku itu mudah dimengerti.
• Buku itu mudah dipahami.

Because Indonesian, like English, can join two descriptions with one and.

So:

• bagus = good
• mudah dimengerti = easy to understand

Together:

• bagus dan mudah dimengerti = good and easy to understand

This is just standard coordination of two adjectives/descriptive phrases.

Yes, in informal writing you may see it without a comma:

• Menurut saya buku sejarah itu bagus dan mudah dimengerti.

But the comma is helpful because Menurut saya is an introductory opinion phrase. In careful writing, the comma makes the sentence easier to read.

So:

• with comma = clearer and more polished
• without comma = still understandable, especially in casual contexts

Yes, but the tone changes.

• Menurut saya = neutral, polite, standard
• Menurutku = more casual, personal
• Menurut aku also exists, but menurutku is more natural

So in casual speech, someone might say:

• Menurutku, buku sejarah itu bagus dan mudah dimengerti.

In formal or neutral contexts, Menurut saya is safer.

Yes, that is possible.

These are both natural:

• Menurut saya, buku sejarah itu bagus dan mudah dimengerti.
• Buku sejarah itu, menurut saya, bagus dan mudah dimengerti.

The difference is mostly about emphasis.

• Starting with Menurut saya emphasizes that this is your opinion.
• Putting buku sejarah itu first emphasizes the book, then adds menurut saya as a comment.

Both are grammatical and common.

A rough pronunciation guide is:

• di-meng-er-ti

Approximate English-style help:

• dee-mung-er-tee

A few notes:

• di- is a prefix here, not the separate preposition di meaning in/on/at
• the ng sound is like the sound in sing
• stress in Indonesian is usually not as strong or dramatic as in English, so it is best spoken fairly evenly

No, not in this sentence, because the noun phrase is clearly:

• buku sejarah itu

This means that history book / the history book.

The word itu is attached to the whole noun phrase, not just to sejarah in the sense of that history. The natural reading is definitely about a particular book.

It is generally neutral to slightly formal, and very natural.

Why:

• Menurut saya sounds polite and standard
• saya is neutral/polite
• the rest of the sentence uses normal everyday vocabulary

So this sentence would fit well in:

• class discussion
• writing practice
• a book review
• polite conversation

A more casual version might be:

• Menurutku, buku sejarah itu bagus dan gampang dimengerti.

But the original sentence is excellent standard Indonesian.