kono hon ha omosiroi desu. demo, sukosi muzukasii desu.

この must be followed by a noun. It means this + noun, so この本 = this book.

By contrast:

• これ = this one / this
• この = this used directly before a noun

So:

• これは面白いです。 = This is interesting.
• この本は面白いです。 = This book is interesting.

You cannot say これ本 in standard Japanese.

は marks the topic of the sentence. It tells the listener what you are talking about.

So この本は面白いです means something like:

• As for this book, it is interesting.
• more naturally: This book is interesting.

A very important point: although it is written は, here it is pronounced わ.

This is a special historical spelling rule in Japanese.

When は is used as the topic particle, it is pronounced wa. When it is part of a normal word, it is usually pronounced ha.

Examples:

• この本は面白いです。 → wa
• はな = flower → ha

So in this sentence, say kono hon wa omoshiroi desu.

Yes. 面白い and 難しい are い-adjectives, and they can work as predicates by themselves.

So both of these are grammatical:

• この本は面白い。
• この本は面白いです。

The difference is politeness:

• 面白い = plain/casual
• 面白いです = polite

The です here adds politeness. It does not change the core meaning.

The same is true for 難しいです.

面白い can mean both interesting and funny/amusing, depending on context.

With 本 (book), the most natural meaning is usually interesting.

So here, この本は面白いです would normally be understood as:

• This book is interesting.

If the context were comedy or jokes, it could lean more toward funny.

でも means but.

It connects the two ideas:

• This book is interesting.
• But it is a little difficult.

So the full sentence expresses contrast: the book is enjoyable, but it also has some difficulty.

It could say that, and it would still be correct:

• でも、この本は少し難しいです。

But Japanese often leaves out words that are already understood from context.

Since the first sentence already established this book as the topic, the second sentence can simply continue with:

• でも、少し難しいです。

The listener naturally understands that the speaker is still talking about this book.

This kind of omission is very common in Japanese.

少し means a little or a bit.

In 少し難しいです, it modifies 難しい, so the meaning is:

• a little difficult
• a bit difficult

It comes before the adjective it modifies, which is normal in Japanese.

So:

• 少し難しいです = It is a little difficult.

In Japanese, when an adjective is the main description of the sentence, it comes before です.

Pattern:

• [topic] は [adjective] です

So:

• この本は面白いです。
• この本は難しいです。

This is different from English, where we use is before the adjective:

• This book is interesting.

In Japanese, the adjective itself carries the descriptive meaning, and です adds politeness.

The basic word order here is the natural one:

• この本は面白いです。
• でも、少し難しいです。

Japanese is often described as more flexible than English, but that does not mean words can be moved freely without changing nuance or sounding unnatural.

For beginners, it is best to remember:

• topic first
• descriptive word later
• polite ending です at the end

So this sentence is a very standard and natural pattern.

No. Japanese is normally written without spaces.

The standard writing would be:

この本は面白いです。でも、少し難しいです。

Spaces are often added in beginner materials to make it easier to see the parts of the sentence.

So the spaced version is for learning, not normal Japanese writing.

Yes. ちょっと and 少し can both mean a little.

So both are natural:

• 少し難しいです
• ちょっと難しいです

A rough difference:

• 少し sounds a bit more neutral or slightly more formal
• ちょっと sounds very common in everyday speech

In this sentence, either works well.

It is polite, because it uses です.

Levels, roughly:

• この本は面白い。でも、少し難しい。 → casual/plain
• この本は面白いです。でも、少し難しいです。 → polite

This is a very common style for everyday polite conversation.

It is not extremely formal, but it is appropriate in many normal situations, especially for learners.