Variasjonen mellom arbeidsstillingene reduserer belastningen.

Because variasjonen is the definite singular form of variasjon.

• variasjon = variation
• variasjonen = the variation

In Norwegian, definiteness is usually added as an ending on the noun instead of using a separate word like English the.

It is a compound noun plus a plural definite ending:

• arbeid = work
• stilling = position / posture
• arbeidsstilling = work position / working posture
• arbeidsstillingene = the work positions / the working postures

So the word is built like this:

• arbeid + stilling + ene

The -ene ending marks definite plural.

Because arbeidsstillingene means the work positions, while arbeidsstillinger means simply work positions.

• arbeidsstillinger = indefinite plural
• arbeidsstillingene = definite plural

Norwegian often uses the definite form where English might sound more general. In a sentence like this, arbeidsstillingene can refer to the set of positions being discussed in a general practical sense.

Because Norwegian usually puts definiteness on the noun itself:

• variasjonen = the variation
• arbeidsstillingene = the work positions
• belastningen = the strain / the load

This is one of the most important differences from English. Instead of writing a separate article before the noun, Norwegian often adds an ending:

• -en / -a / -et for singular definite
• -ene / -a for plural definite

Mellom means between or sometimes among, depending on context.

In this sentence, mellom arbeidsstillingene means something like:

• between the work positions
• among the different work positions

So Variasjonen mellom arbeidsstillingene means that the variation exists across or between those positions.

Reduserer is the present tense of å redusere.

• å redusere = to reduce
• reduserer = reduces / is reducing

A very useful thing about Norwegian verbs is that they do not change for person:

• jeg reduserer
• du reduserer
• han/hun reduserer
• vi reduserer

The form stays the same.

This is normal Norwegian main clause word order:

• Variasjonen = subject
• reduserer = verb
• belastningen = object

So it follows the basic pattern:

subject + verb + object

Norwegian is also a V2 language, which means the finite verb normally comes in the second position in main clauses. Since the subject comes first here, the verb naturally comes right after it.

Belastningen is the definite singular form of belastning.

• belastning = strain / load / stress
• belastningen = the strain / the load / the stress

In Norwegian, definite forms are often used in general statements where English might sometimes prefer no article or a different phrasing. Here it refers to the relevant strain being discussed in the situation.

Usually not in this context.

Although stilling can mean position, the compound arbeidsstilling commonly means working position or work posture—that is, the physical position your body is in while working.

So here it is about posture or body position, not about a job title.

In theory, you might see more indefinite wording in some contexts, but this sentence sounds natural with definite nouns.

Norwegian often uses definite forms in general or technical statements more freely than English does. So a native English speaker may expect something more like variation between work positions reduces strain, but Norwegian is very comfortable with:

• variasjonen
• arbeidsstillingene
• belastningen

Even when the statement is fairly general.

A native speaker would probably process it like this:

• Variasjonen = the variation
• mellom arbeidsstillingene = between/among the work positions
• reduserer = reduces
• belastningen = the strain

So the sentence is built around one clear subject:

Variasjonen mellom arbeidsstillingene

That whole noun phrase is the thing doing the action, and the action is reduserer.

Yes—three things:

1. Definiteness is built into the noun

   • variasjonen, arbeidsstillingene, belastningen

2. Compound nouns are very common

   • arbeidsstilling is one word, not two

3. The verb form is simple

   • reduserer does not change with the subject

Those three features show up constantly in Norwegian, so this sentence is a very useful model.