Hviledagen kommer etter langturen.

Because Norwegian usually writes compound nouns as a single word.
Hviledag is made from hvile + dag.

This is very common in Norwegian:

• hvile = rest
• dag = day
• hviledag = rest day

English often uses two words where Norwegian uses one compound word.

The -en ending is the definite article, so it works like the in English.

• hviledag = a rest day
• hviledagen = the rest day
• langtur = a long run / long outing / long trip, depending on context
• langturen = the long run / the long outing / the long trip

So instead of putting a separate word like the before the noun, Norwegian often adds the definiteness to the end of the noun.

The ending is -en here because dag and tur are common-gender nouns in Bokmål.

Because langtur is being treated as a compound noun, not as an adjective + noun phrase.

There are two different structures:

• langturen = the definite form of the compound noun langtur
• den lange turen = the long trip/run, with lang used as a separate adjective

Both can be grammatical, but they are not always used in exactly the same way.

In many exercise or outdoor contexts, langtur is a set expression, so langturen can sound more natural than den lange turen. It feels more like a named type of session or activity, such as the long run.

In Norwegian, komme can be used both literally and figuratively.

Here it is figurative. Kommer etter means something like:

• comes after
• follows
• is next after

So kommer does not have to mean physical movement. It can also describe order, sequence, or what happens next.

Norwegian often uses the present tense for:

• general truths
• routines
• schedules
• planned sequences

So Hviledagen kommer etter langturen can describe the normal order of things. This is similar to English sentences like:

• Monday comes after Sunday.
• The meeting starts at 10.
• The easy day comes after the hard workout.

A future form is not necessary here.

This is normal Norwegian main-clause word order:

Hviledagen + kommer + etter langturen

So:

• Hviledagen = subject
• kommer = finite verb
• etter langturen = adverbial phrase

Norwegian is a V2 language, which means the finite verb normally comes in the second position in a main clause.

In this sentence, the subject comes first, so the verb comes right after it.

Yes, absolutely. That is also correct.

When you move etter langturen to the front, you are emphasizing the sequence or time relationship a bit more:

• Hviledagen kommer etter langturen
• Etter langturen kommer hviledagen

Both mean the same basic thing.

The important grammar point is that Norwegian still keeps the finite verb in second position, so when etter langturen comes first, kommer must come next, before hviledagen.

The difference is definiteness.

• etter langturen = after the long run / after that specific long run
• etter en langtur = after a long run / after any long run

So the sentence you were given refers to a specific rest day and a specific long run, or to a known sequence in a plan.

If you used en langtur, it would sound more general.

Usually, no, not in normal everyday Norwegian.

With singular countable nouns like these, Norwegian normally wants either:

• an indefinite form with an article: en hviledag, en langtur
• or a definite form: hviledagen, langturen

So these are natural:

• En hviledag kommer etter en langtur.
• Hviledagen kommer etter langturen.

But bare singular forms like hviledag and langtur without any article or definite ending usually sound unnatural in an ordinary sentence like this.