Banken forklarer rentestresstesten for låntakeren.

Because banken is the definite singular form of bank.

• bank = a bank
• banken = the bank

In Norwegian, many common-gender nouns add -en to show definiteness, instead of using a separate word like English the.

Forklarer is the present tense of å forklare, which means to explain.

• å forklare = to explain
• forklarer = explains / is explaining

In Norwegian, the present tense often covers both the English simple present and present progressive, depending on context.

Because Norwegian usually writes compound nouns as one word.

This word can be broken down like this:

• rente = interest / interest rate
• stress
• test
• -en = the definite ending

So rentestresstesten is a compound noun meaning something like the interest-rate stress test.

A very important rule in Norwegian is that compound nouns are normally written together, where English often uses two or more separate words.

For the same reason as banken: it is definite singular.

• rentestresstest = an interest stress test
• rentestresstesten = the interest stress test

In Norwegian, the last part of a compound noun decides how the whole word behaves grammatically. Since the last part is test, the whole compound inflects like test.

Here, for means something like English to, not necessarily for in the usual sense.

With forklare, Norwegian commonly uses this pattern:

• forklare noe for noen = explain something to someone

So:

• rentestresstesten = the thing being explained
• for låntakeren = to the borrower

This is a very natural Norwegian construction.

Because låntakeren means the borrower and is also definite singular.

• låntaker = a borrower
• låntakeren = the borrower

The noun låntaker is made from:

• lån = loan
• taker = taker / one who takes

So it literally means something like loan-taker, which corresponds to English borrower.

That would usually sound unnatural or wrong in standard Norwegian.

The normal pattern is:

• Banken forklarer rentestresstesten for låntakeren.

Norwegian generally prefers forklare noe for noen rather than putting the person directly after the verb in this kind of sentence.

So for learners, it is safest to remember:

• forklare noe for noen

The sentence follows a very common Norwegian pattern:

• Banken = subject
• forklarer = verb
• rentestresstesten = direct object
• for låntakeren = prepositional phrase

So the structure is:

Subject + Verb + Object + Prepositional phrase

That is a normal main-clause word order in Norwegian.

Not in the same way. Modern Norwegian mostly does not show noun case with endings like German.

Here, the roles are mainly shown by:

• word order
• prepositions

So you understand who is doing what mostly from the sentence structure:

• Banken does the explaining
• rentestresstesten is what is explained
• for låntakeren shows who receives the explanation

The verb would come first:

• Forklarer banken rentestresstesten for låntakeren?
• Does the bank explain the interest stress test to the borrower?

This is very common in Norwegian yes/no questions.

No. Norwegian does not capitalize all nouns the way German does.

Banken is capitalized here only because it is the first word of the sentence. If it appeared in the middle of a sentence, it would normally be written banken.