Fokuseringen begynner i skumringen.

Because -en marks the definite singular form of the noun in Bokmål. So:

• fokusering = focusing / focus
• fokuseringen = the focusing / the focus

In other words, Norwegian often attaches the equivalent of the to the end of the noun instead of putting a separate word in front.

It is a noun.

It comes from the verb å fokusere (to focus) and has the ending -ing, which often creates a noun related to an action, similar to English -ing words:

• å fokusere = to focus
• fokusering = focusing

So in this sentence, fokuseringen is the thing that is beginning; that is why it functions as the subject of the sentence.

Begynner is the present tense of å begynne (to begin / to start).

Forms:

• å begynne = infinitive
• begynner = present tense
• begynte = past tense
• har begynt = has/have begun

Norwegian uses the same present-tense form for all persons:

• jeg begynner
• du begynner
• han/hun begynner
• vi begynner

So there is no extra -s like English begins.

Because i is the preposition needed here to express in / at during that time period.

• i skumringen = in the twilight / at dusk

Norwegian often uses i with periods or environments:

• i mørket = in the dark
• i solen = in the sun
• i skumringen = in the twilight

So i helps show when the action begins.

In Norwegian, expressions for times of day or phases of light often use the definite form where English may use no article or a different structure.

So:

• i skumringen is the normal way to say at dusk / in the twilight

Using i skumring would sound less natural in standard everyday Bokmål. The definite form makes the expression sound complete and idiomatic.

This is similar to other Norwegian time expressions such as:

• om morgenen = in the morning
• om kvelden = in the evening
• i mørket = in the dark

The sentence follows normal Norwegian main-clause word order:

• Fokuseringen = subject
• begynner = verb
• i skumringen = time phrase

So the pattern is basically:

Subject + verb + adverbial

This is the standard order in a simple statement.

Yes. That is also grammatical.

If you move the time phrase to the front, Norwegian still keeps the verb in second position:

• Fokuseringen begynner i skumringen.
• I skumringen begynner fokuseringen.

This is a very important Norwegian rule called V2 word order in main clauses. When something other than the subject comes first, the verb still stays second, so the subject moves after the verb.

It is understandable and grammatically fine, but it can sound a bit formal, technical, or abstract, depending on context.

Norwegian often prefers a verb if the style is meant to be simpler or more direct. For example, in some contexts a sentence with å fokusere might sound more natural than a heavy noun like fokuseringen.

But whether it feels natural really depends on the topic:

• in technical writing, instructions, or academic language, fokuseringen can sound perfectly normal
• in casual speech, a more verbal phrasing may be more likely

They both appear in the definite singular form, which is why they both end in -en here.

• fokusering → fokuseringen
• skumring → skumringen

That does not necessarily mean they are identical in every grammatical way; it simply means the sentence is using the definite singular form for both nouns.

Also, in Bokmål, many nouns that can be treated as feminine are often written with -en as well, so -en is very common in actual usage.

Usually, no. Norwegian normally uses the simple present:

• begynner

That can often correspond to either:

• begins
• is beginning

The exact English translation depends on context. Norwegian does not usually need a separate progressive form the way English does.