Evnen er viktig.

The base form is evne.

• en evne = an ability
• evnen = the ability

So evnen is the definite singular form of the noun.

It is also a common gender noun in Norwegian, so its dictionary form is en evne.

Because Norwegian usually marks the by adding an ending to the noun.

For a common gender noun:

• en evne = an ability
• evnen = the ability

That -en ending is the normal singular definite ending for many common gender nouns.

Compare:

• en bil → bilen = the car
• en tanke → tanken = the thought

So evnen already includes the idea of the.

Because in Norwegian, definiteness is often built into the noun itself.

So instead of saying a separate word like English the ability, Norwegian can simply say:

• evnen

You can sometimes see an extra determiner such as den, but not in a simple sentence like this.

For example:

• den viktige evnen = the important ability

Here, den appears because there is an adjective before the noun. But in Evnen er viktig, the noun can stand on its own with the definite ending.

Er means is.

It is the present tense of å være, which means to be.

A few forms are:

• å være = to be
• er = am / is / are
• var = was / were
• har vært = has/have been

So Evnen er viktig is a very straightforward present-tense sentence.

Because viktig is the correct form here for a singular subject in this kind of sentence.

The structure is:

• subject + er
  • adjective

In this sentence, evnen is singular, so viktig is correct.

Compare:

• Evnen er viktig. = The ability is important.
• Evnene er viktige. = The abilities are important.

A useful detail: the adjective viktig has the same form in both common singular and neuter singular, so you do not see a change here.

Compare with an adjective where the form changes more clearly:

• Bilen er stor. = The car is big.
• Huset er stort. = The house is big.
• Bilene er store. = The cars are big.

So the pattern is normal; viktig just happens to look the same in the singular forms.

Yes. This is the basic pattern for a simple main clause:

• subject + verb + complement

So here:

• Evnen = subject
• er = verb
• viktig = subject complement / predicate adjective

This is one of the most basic Norwegian sentence patterns.

If something else comes first, Norwegian usually keeps the finite verb in second position:

• I denne jobben er evnen viktig. = In this job, the ability is important.

So the simple sentence you were given uses completely normal word order.

The difference is indefinite vs. definite:

• evne = ability / an ability
• evnen = the ability

This is a very common distinction in Norwegian nouns.

Examples:

• Hun har en evne til å lytte. = She has an ability to listen.
• Evnen til å lytte er viktig. = The ability to listen is important.

So in your sentence, evnen points to a specific or understood ability.

A rough English-friendly guide is:

• EV-nen er VIK-ti

A few pronunciation notes:

• Evnen has stress on the first syllable: EV-nen
• viktig also has stress on the first syllable: VIK-ti
• the final g in viktig is often not pronounced like a hard English g
• er is usually short and light in normal speech

Do not worry too much about making it perfect at first; the main thing is to stress the first syllable of evnen and viktig.

No. Norwegian nouns are not capitalized the way German nouns are.

Evnen is capitalized here only because it is the first word of the sentence.

So:

• Evnen er viktig.
• Denne evnen er viktig.

In the second sentence, evnen is no longer sentence-initial, so it is written with a lowercase e.