Een vaardigheid is belangrijk.

Een is the Dutch indefinite article, like English a or an.

So een vaardigheid means a skill.

A few useful things to know:

• een is used with singular countable nouns
• the plural has no article here: vaardigheden zijn belangrijk = skills are important
• een can also mean one, but then it is stressed more strongly in speech

In this sentence, it is just the ordinary article: a.

It is a de word: de vaardigheid.

A very helpful rule is that nouns ending in -heid are almost always de words.
So:

• de vaardigheid
• de mogelijkheid
• de vrijheid

That matters when you use the definite article or adjective endings later.

Because belangrijk is not being used before a noun here. It is being used after the verb is, as a predicate adjective.

Compare:

• Een vaardigheid is belangrijk.
  Here belangrijk comes after is, so it stays in its basic form.

• Een belangrijke vaardigheid.
  Here it comes before the noun vaardigheid, so it usually gets -e.

This is very common in Dutch:

• De man is groot.
• Het huis is groot.
• Een grote man
• Een groot huis

So in your sentence, belangrijk is correct because it is a predicate adjective.

This is the normal word order for a simple Dutch main clause:

subject + finite verb + rest

So:

• Een vaardigheid = subject
• is = finite verb
• belangrijk = predicate adjective

Dutch is a verb-second language in main clauses, which means the finite verb normally comes in the second position.

That is why:

• Een vaardigheid is belangrijk. is correct
• Een vaardigheid belangrijk is. is not normal main-clause word order

You may see the verb later in subordinate clauses, but not in a basic sentence like this.

Is is the third-person singular present tense of zijn = to be.

Here it matches the singular subject een vaardigheid.

A few forms of zijn in the present tense are:

• ik ben
• jij bent / ben jij
• hij/zij/het is
• wij zijn
• jullie zijn
• zij zijn

So vaardigheid is singular, and therefore Dutch uses is.

Yes, but it changes the feel of the sentence.

• Een vaardigheid is belangrijk. = A skill is important / One skill is important
• Vaardigheid is belangrijk. = Skill is important in a more general, abstract sense

Without een, the noun sounds more like a general concept rather than one individual skill.

English does something similar:

• A skill is important
• Skill is important

The version with een is often the more natural direct match for the sentence you were given.

The plural is vaardigheden.

So the plural sentence would be:

Vaardigheden zijn belangrijk.

Changes:

• vaardigheid → vaardigheden
• is → zijn

This is because the subject becomes plural.

Usually een is pronounced very weakly, something like uhn or just a schwa-like sound.

In normal speech, it is often not pronounced like the English word one.

Roughly:

• unstressed article een → uhn / ə(n)
• stressed number één = one → pronounced more clearly

So in Een vaardigheid is belangrijk, the article is usually unstressed.

A rough English-friendly guide:

• vaardigheid ≈ VAHR-dukh-hite
• belangrijk ≈ buh-LANG-rike

A few pronunciation notes:

vaardigheid

• v in Dutch is often somewhere between English v and f
• aa is a long vowel, like a long a
• g is the Dutch guttural sound, not an English g
• -heid sounds a bit like hite

belangrijk

• ij is a Dutch diphthong, often roughly like eye
• the stress is usually on lang
• g again is the guttural Dutch sound

If you want a simpler learner version, you can remember:

• vaardigheid → stress near the start
• belangrijk → stress on lang

Yes. It is related to vaardig, which means something like skilled, adept, or proficient.

The ending -heid is a common noun-forming suffix, similar to English -ness.

So very roughly:

• vaardig = skilled
• vaardigheid = skill / skillfulness

This pattern is very useful in Dutch. For example:

• vrij → vrijheid
• mogelijk → mogelijkheid

So learning -heid as a common noun ending can help you recognize many words.

Because Dutch does not have a separate article like English an.

English changes:

• a skill
• an idea

Dutch keeps een in both cases:

• een vaardigheid
• een idee

So you do not need to worry about changing the article depending on the next sound. Dutch simply uses een.