Når det gjelder fellesperioden, kan den deles.

Når det gjelder is a very common expression meaning when it comes to, regarding, or as for.

Even though når often means when, here the whole phrase is not really about time. It introduces a topic.

So in this sentence, Når det gjelder fellesperioden means something like:

• As for the common period
• When it comes to the common period
• Regarding the common period

It is best learned as a set phrase.

The comma separates the introductory part from the main clause.

In Norwegian, when a subordinate or introductory clause comes first, it is normally followed by a comma. Here, Når det gjelder fellesperioden sets up the topic, and then the main statement comes after it:

• Når det gjelder fellesperioden, = introductory/topic-setting part
• kan den deles = main clause

So the comma is standard and helps show the structure of the sentence.

This is because of the Norwegian V2 rule in main clauses.

Norwegian usually puts the finite verb in the second position of a main clause. When something is moved to the front of the sentence, the verb still has to stay in second position.

Here, the first position is taken by the introductory phrase:

• Når det gjelder fellesperioden = position 1

So the finite verb must come next:

• kan = position 2

Then comes the subject:

• den

That is why you get:

• Når det gjelder fellesperioden, kan den deles.

Compare:

• Fellesperioden kan deles.
• Når det gjelder fellesperioden, kan den deles.

But not standard:

• Når det gjelder fellesperioden, den kan deles.

Because Norwegian usually writes compound nouns as a single word.

So:

• felles = common/shared/joint
• perioden = the period

Together:

• fellesperioden = the common/shared period

This is very normal in Norwegian. English often writes similar things as two words, but Norwegian prefers one compound word.

Examples of the same pattern:

• sommerferie = summer vacation
• arbeidsdag = workday
• barnebok = children’s book

The ending -en marks the noun as definite singular.

The base noun is periode = period.
In the definite singular, it becomes perioden = the period.

Inside the compound, the whole word becomes definite:

• fellesperiode = a common/shared period
• fellesperioden = the common/shared period

So -en here works like the in English.

Den refers back to fellesperioden.

Norwegian often avoids repeating the noun and uses a pronoun instead, just like English uses it.

It is den because periode is a common gender noun. In Norwegian:

• common gender nouns usually take den
• neuter nouns usually take det

So:

• perioden → den
• if it were a neuter noun, you would expect det

Deles is the -s passive form of the verb dele.

• dele = to divide / to split / to share
• deles = be divided / be split / be shared

So kan den deles means can it be divided/shared.

Norwegian has two common ways to make the passive:

1. -s passive
   • den deles
2. bli + past participle
   • den blir delt

In many cases both are possible, though the -s form is often shorter and more compact.

Kan can express several related ideas in Norwegian, just like can in English.

Depending on context, it may mean:

• is able to
• may
• is possible to

In this sentence, it most naturally expresses possibility:

• kan den deles = it can be divided / it may be divided

It is not necessarily talking about physical ability. It could also imply that division is allowed or practically possible, depending on the wider context.

Yes. Some natural alternatives are:

• Fellesperioden kan deles.
• Når det gjelder fellesperioden, kan man dele den.
• Fellesperioden kan bli delt.

These are all slightly different in style:

• Fellesperioden kan deles is the most direct.
• Når det gjelder fellesperioden, ... sounds more like as for the common period...
• kan man dele den uses an active structure, literally can one divide it.
• kan bli delt uses another passive pattern.

A less natural version in standard Norwegian would be:

• Når det gjelder fellesperioden, den kan deles.

That sounds wrong because it breaks the usual verb-second word order in the main clause.