marui teeburu yori, sikakui tukue no hou ga hon wo okiyasui desu.

This is a very common comparison pattern in Japanese:

A より、B のほうが C
= B is more C than A

So here:

• 丸いテーブルより = than a round table
• 四角い机のほうが = a square desk is the one that...
• 本を置きやすいです = is easier to place books on

So the whole sentence means that a square desk is easier to put books on than a round table.

ほう literally means something like side, direction, or one of the two options.

In comparisons, B のほうが means B, rather, B is the one that..., or more naturally just B as the compared item.

So:

• 四角い机のほうが = the square desk (rather than the other option)

It helps mark which of the two things has the quality being compared.

A very literal way to think of it is:

• 丸いテーブルより = compared to a round table
• 四角い机のほうが = the square-desk side is...

That sounds strange in English, but it is the basic idea.

The の connects the noun phrase 四角い机 to ほう.

So:

• 四角い机 = square desk
• 四角い机のほう = the square-desk one / the square-desk side

This is a normal way to attach ほう to a noun phrase in comparisons.

The が marks the subject of the sentence.

The thing being described as easy to place books on is 四角い机のほう.

So:

• 四角い机のほうが = the square desk is the one that...

Then the rest says what is true about it:

• 本を置きやすいです = is easy to place books on

So が is marking the item that has the quality.

Both 丸い and 四角い are い-adjectives, so they can directly modify nouns.

• 丸いテーブル = a round table
• 四角い机 = a square desk

This is just like other い-adjectives:

• 大きい犬 = a big dog
• 新しい本 = a new book

So there is nothing special you need between the adjective and the noun.

置きやすい means easy to put or easy to place.

It is formed from:

• 置く = to put / place
• verb stem: 置き
• やすい = easy to do

So:

• 置く → 置きやすい = easy to place

This pattern is very useful:

• 読みやすい = easy to read
• 使いやすい = easy to use
• 分かりやすい = easy to understand

In this sentence, 本を置きやすい means easy to place books or, more naturally in English here, easy to place books on.

Because 本 is the direct object of 置く.

• 本を置く = to place a book / books

So を marks the thing being placed.

Even though English often says place books on it, Japanese is focusing on books as the object of the action.

Yes, in a full sentence you often would say:

• 机に本を置く = put a book on the desk

But here, 机 and テーブル are the things being compared, not just the location inside the verb phrase.

The location idea is understood from context. The sentence is basically saying:

• As for which surface is easier for placing books, the square desk is easier than the round table.

So Japanese leaves the on it part implicit.

You could think of the fuller idea as something like:

• 四角い机のほうが、本をその上に置きやすいです。

But that would usually sound unnecessarily explicit.

Yes, 置きやすいです is correct.

置きやすい behaves like an い-adjective, and です can be added after an い-adjective to make the sentence polite.

So:

• casual: 本を置きやすい
• polite: 本を置きやすいです

This is very normal:

• 大きいです = it is big
• 難しいです = it is difficult
• 使いやすいです = it is easy to use

In general:

• テーブル = table
• 机 = desk

机 usually suggests something used for work, study, or writing.
テーブル is a more general table, such as a dining table or coffee table.

So the sentence is contrasting:

• a round table
• a square desk

That may also suggest a practical difference: a square desk often has corners and straight edges, which can make arranging books easier.

It can mean either, depending on context.

Japanese nouns usually do not change form for singular vs. plural the way English nouns do. So:

• 本 can mean a book
• 本 can also mean books

In this sentence, English naturally uses books, because it sounds like a general statement about putting books on furniture.

Yes. Japanese word order is somewhat flexible as long as the particles make the roles clear.

For example, this would also work:

• 四角い机のほうが、丸いテーブルより、本を置きやすいです。

This still means the same thing: A square desk is easier to place books on than a round table.

The original version starts with 丸いテーブルより, which sets up the comparison first. That is a very natural way to say it.

No, the comma is not grammatically required.

It just helps show a pause after the comparison phrase:

• 丸いテーブルより、四角い机のほうが...

Without the comma, the meaning stays the same:

• 丸いテーブルより四角い机のほうが本を置きやすいです。

The spaces in the sentence are also just for readability for learners. In normal Japanese writing, you would usually write it without spaces.