kyuumei no rensa ha taisetu desu.

A natural reading is:

きゅうめい の れんさ は たいせつ です
Kyūmei no rensa wa taisetsu desu.

A few notes:

• 救命 = きゅうめい
• 連鎖 = れんさ
• は is written は but pronounced わ when it is the topic particle
• 大切 = たいせつ

の connects nouns. It often works like:

• of
• possessive 's
• a noun modifier

So 救命の連鎖 literally looks like chain of lifesaving / lifesaving chain.

In smoother English, this is often understood as the chain of survival.

Yes, it can be. In medical or emergency-response contexts, 救命の連鎖 is a recognized expression corresponding to the chain of survival.

That matters because the phrase may sound a little more fixed and technical than if you translated each part separately word by word.

は marks the topic: what the sentence is about.

So 救命の連鎖は大切です means something like:

• As for the chain of survival, it is important.
• The chain of survival is important.

If you used が, the sentence would sound more like you are specifically identifying or emphasizing that this is the important thing. But with は, it feels like a general statement about the topic.

For a learner, the easiest takeaway is:

• は = topic / general statement
• が = subject / focus / identification

This is one of the standard exceptions in Japanese spelling.

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

So in this sentence:

• written: 連鎖は
• pronounced: れんさわ

The same kind of thing happens with some other particles too, such as へ, which is often pronounced e when used as a particle.

Yes, 大切 is what learners usually call a na-adjective.

That means it behaves differently from an i-adjective like 大きい.

Examples:

• 大切なもの = an important thing
• 大切です = is important
• 大切だ = is important / important (plain style)

So in this sentence, 大切です is the polite predicate.

Good question. な is only used when a na-adjective directly modifies a noun.

So:

• 大切な本 = an important book
  
  • here, 大切 modifies 本, so you need な

But:

• 本は大切です = Books are important
  
  • here, 大切 is the predicate, so you do not use な

That is why 救命の連鎖は大切です is correct, not 大切なです.

です makes the sentence polite.

So:

• 救命の連鎖は大切です = polite
• 救命の連鎖は大切だ = plain
• 救命の連鎖は大切 = conversational / less complete-sounding in careful writing

In textbooks, です is often introduced early as the polite sentence ending used with nouns and na-adjectives.

No, standard Japanese normally does not use spaces between words.

So the normal written sentence is:

救命の連鎖は大切です。

Spaces are often added in teaching materials to help beginners see the parts more clearly.

Yes, in a sense. Japanese very often leaves out things that are understood from context.

In English, you usually need a subject, but in Japanese you often do not. Here, the topic 救命の連鎖 is enough.

So instead of needing something like It is important, Japanese simply says:

救命の連鎖は大切です

The sentence is complete as it is.

Yes, often it could.

• 大切です = important, valuable, precious
• 大事です = important, important to take care with; sometimes also serious depending on context

In this sentence, both 大切です and 大事です could work, but 大切 can sound slightly more thoughtful or value-oriented. The exact nuance depends on context.

It is polite and fairly neutral.

• です makes it polite
• The vocabulary, especially 救命の連鎖, sounds somewhat formal or technical because of the medical/emergency context

So it would fit well in:

• educational materials
• public safety information
• presentations
• announcements

It is not extremely stiff, but it is not casual conversation either.

A plain-style version would be:

救命の連鎖は大切だ。

In everyday conversation, someone might also say:

救命の連鎖って大切だよね。

That sounds more conversational, with って marking the topic in a casual way and よね adding a tone like you know / right.

The structure is:

[noun phrase] + は + [na-adjective] + です

In this case:

• 救命の連鎖 = noun phrase
• は = topic marker
• 大切 = na-adjective
• です = polite copula

So this is a very common and useful Japanese sentence pattern.