kono zyouhou ha daizi desu.

No. Japanese is normally written without spaces:

この情報は大事です。

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

この means this and must be followed by a noun.

• この情報 = this information

By contrast, これ means this by itself:

• これは大事です。 = This is important.

So:

• この
  • noun
• これ = standalone pronoun

Because この directly modifies the noun that comes after it.

In Japanese, words like この / その / あの attach straight to a noun:

• この情報 = this information
• その本 = that book
• あの人 = that person

So you do not say このの情報 or put a particle between この and 情報.

は marks the topic of the sentence.

So in:

この情報は大事です。

the topic is この情報 (this information), and the sentence says something about it: it is important.

A natural way to think of it is:

• As for this information, it is important.

Also, even though it is written は, here it is pronounced wa.

は and が are often both possible, but they give different nuance.

• この情報は大事です。
  = As for this information, it’s important.
  This sounds like you are talking about this information as a topic.

• この情報が大事です。
  = This information is the important one / It’s this information that is important.
  This can sound more selective or contrastive, depending on context.

For a simple neutral statement in a textbook, は is very common.

Yes, 大事 means important, but grammatically it behaves like a na-adjective.

With a noun, it becomes:

• 大事な情報 = important information

At the end of a polite sentence, it can appear as:

• この情報は大事です。

So です is the polite sentence ending here.

You can think of 大事 as an adjective-like word that often works with です in polite speech.

Because 大事 is not an -i adjective. It is a na-adjective.

Compare:

• 高い = expensive/high (i-adjective)
• 大事 = important/precious (na-adjective)

That means:

• 高いです
• 大事です

And before a noun:

• 高い本
• 大事な本

So 大事い is incorrect.

In beginner translations, です is often matched with is, but it is better to think of it as a polite sentence ending rather than a perfect one-to-one equivalent of English is.

In this sentence:

この情報は大事です。

です makes the sentence polite and complete.

A casual version would be:

• この情報は大事だ。
  or even
• この情報は大事。

Yes, この情報は大事です。 is polite.

Casual versions include:

• この情報は大事だ。
  Plain style
• この情報は大事。
  Very casual, common in conversation

If you are speaking to strangers, teachers, customers, or in formal situations, です is the safer choice.

Yes. 大事 can mean more than just important.

Depending on context, it can mean:

• important
• valuable
• precious
• cherished

For example:

• これは大事な本です。
  This is an important book. / This is a treasured book.

So the exact nuance depends on the situation.

Japanese often uses 情報 in a broad way, similar to English information.

So:

• この情報 = this information

If you want to count individual items more precisely, Japanese can use counters or other phrasing, but in a sentence like this, 情報 by itself is perfectly natural.

It is pronounced jōhō.

A simple breakdown:

• 情 = jō
• 報 = hō

Both vowels are long:

• じょうほう

And the whole sentence is pronounced roughly:

kono jōhō wa daiji desu

Both can mean important, but the nuance is a little different.

• 大事 often sounds more everyday, personal, or practical
• 重要 often sounds more formal, objective, or official

So:

• この情報は大事です。 = very natural in normal speech
• この情報は重要です。 = also correct, but slightly more formal or technical

Both are good Japanese; the best choice depends on tone and context.