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.
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:
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:
At the end of a polite sentence, it can appear as:
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:
That means:
And before a noun:
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:
Yes, この情報は大事です。 is polite.
Casual versions include:
If you are speaking to strangers, teachers, customers, or in formal situations, です is the safer choice.
Both can mean important, but the nuance is a little different.
So:
Both are good Japanese; the best choice depends on tone and context.