Щеплення важливе.

Because важливе has to agree with щеплення in gender and number.

• щеплення is a neuter singular noun
• So the adjective must also be neuter singular
• That gives важливе

Compare:

• важливий = masculine
• важлива = feminine
• важливе = neuter

So Щеплення важливе is grammatically matching: Vaccination is important / The vaccination is important.

Щеплення is neuter.

A very common clue is the ending -я in nouns like this, especially verbal nouns such as:

• читання = reading
• питання = question
• щеплення = vaccination

Not every noun ending in -я is neuter, but this -ння / -ення pattern is very often neuter.

That is why it takes the neuter adjective form важливе.

In Ukrainian, the verb to be is usually not expressed in the present tense.

So where English says:

• Vaccination is important

Ukrainian normally says:

• Щеплення важливе

The idea of is is understood automatically.

If you wanted past or future, then forms of бути would appear, for example:

• Щеплення було важливе = The vaccination was important
• Щеплення буде важливе = The vaccination will be important

It can mean a few closely related things depending on context.

Most commonly, щеплення can mean:

• vaccination
• a vaccination shot
• an inoculation

In some contexts it can even refer more generally to grafting in plants, because the word is historically related to the idea of inserting/grafting.

So in everyday medical language, щеплення usually means vaccination or a vaccine shot.

A rough English-style guide is:

• Щеплення ≈ shchep-LEHN-nya
• важливе ≈ vahzh-LY-ve

A few notes:

• щ is usually pronounced like a soft long shch
• е is like e in met, not like English ee
• я at the end of щеплення sounds like ya
• The stress is usually:
  • щеплЕння
  • важлИве

Stress matters in Ukrainian, so it is helpful to learn it with the word.

It is in the nominative case.

That is because щеплення is the subject of the sentence:

• Щеплення = the thing being talked about
• важливе = what is being said about it

This is a basic subject + predicate adjective structure, and in sentences like this, both words are normally in the nominative.

The most neutral word order is:

• Щеплення важливе.

This is the straightforward way to say Vaccination is important.

Ukrainian word order is fairly flexible, but changing it can affect the feel or meaning.

For example:

• Щеплення важливе. = neutral statement
• Важливе щеплення. = more likely an important vaccination as a noun phrase, not a full sentence in the same neutral way

So if you simply want to say the sentence by itself, Щеплення важливе is the safest and most natural choice.

Yes.

Ukrainian does not have articles like a or the, so щеплення can mean:

• vaccination
• the vaccination
• a vaccination

The exact meaning depends on context.

So Щеплення важливе could mean:

• Vaccination is important
• The vaccination is important
• A vaccination is important

In practice, context tells you which one is meant.

It is a noun, but more specifically it is a verbal noun.

That means it comes from a verb and names an action or process. Here it is related to the verb щепити:

• щепити = to vaccinate / inoculate

So:

• щеплення = vaccination / inoculation

This is similar to English pairs like:

• to vaccinate → vaccination
• to govern → government

Knowing this pattern helps you recognize many Ukrainian nouns ending in -ння or -ення.

Yes, but it changes the meaning slightly.

• Щеплення важливе. = Vaccination is important. / The vaccination is important.
• Це щеплення важливе. = This vaccination is important.

So це adds the idea of this and points to a specific vaccination or shot.

If you want the more general statement, leave це out.