Garantibeviset dokumenterer servicehistorikken.

Because the base noun is et garantibevis = a warranty certificate.

In Norwegian, many nouns add the definite article as a suffix instead of using a separate word like the. So:

• et garantibevis = a warranty certificate
• garantibeviset = the warranty certificate

The ending -et shows that the noun is:

• singular
• definite
• neuter

Norwegian usually puts definiteness at the end of the noun.

So instead of a separate word like English the, you often get:

• beviset = the certificate
• historikken = the history / the record

That is completely normal Norwegian. In this sentence, both nouns are definite:

• Garantibeviset = the warranty certificate
• servicehistorikken = the service history

Because the head noun is historikk, which is a masculine noun in Bokmål: en historikk.

So the forms are:

• en historikk = a history / record
• historikken = the history / record

When it becomes part of the compound servicehistorikk, the gender stays with the head noun historikk, so:

• en servicehistorikk
• servicehistorikken

That is why it ends in -en rather than -et.

Because Norwegian uses compound nouns very freely, much more than English does.

So:

• garanti + bevis → garantibevis
• service + historikk → servicehistorikk

English often writes these as two words or uses hyphens, but Norwegian usually joins them into one word.

This is very common and important to get used to when reading Norwegian.

Because dokumenterer is the present tense form of the verb å dokumentere.

• å dokumentere = to document
• dokumenterer = documents / is documenting

Norwegian verbs do not change for person the way English verbs sometimes do. So the same present-tense form is used with all subjects:

• jeg dokumenterer
• du dokumenterer
• han/hun dokumenterer
• vi dokumenterer

In this sentence, Garantibeviset dokumenterer ... means The warranty certificate documents ...

Yes. It is a very standard Norwegian main-clause pattern:

Subject + verb + object

• Garantibeviset = subject
• dokumenterer = verb
• servicehistorikken = object

So the sentence structure is very straightforward and works much like English here.

Here, service refers to maintenance or servicing, especially for something like a car or machine.

So servicehistorikk means the record/history of maintenance that has been done.

It does not mean customer service in this context.

This use of service is very common in Norwegian, especially with vehicles:

• servicehefte = service book
• serviceavtale = service agreement
• servicehistorikk = service history

The dictionary forms are:

• et garantibevis = a warranty certificate
• å dokumentere = to document
• en servicehistorikk = a service history / service record

The sentence uses inflected forms:

• Garantibeviset = definite singular of et garantibevis
• dokumenterer = present tense of å dokumentere
• servicehistorikken = definite singular of en servicehistorikk

Knowing the dictionary form helps you recognize words when they appear in other sentences.

Because the sentence is referring to specific things, not just any warranty certificate or any service history.

• Garantibeviset = the specific warranty certificate
• servicehistorikken = the specific service history

If you made them indefinite, the meaning would become more general:

• Et garantibevis dokumenterer en servicehistorikk would sound like a general statement: A warranty certificate documents a service history

But the original sentence sounds like it is talking about a particular document and a particular record.