Trappeopgangen er ren, og viceværten hilser venligt om morgenen.

Because Danish very often forms compound nouns as a single word.

• trappe = staircase / stairs
• opgang = entrance hall / stairwell / building entrance

So trappeopgang is a compound noun meaning something like stairwell or the entrance staircase area.

Then the definite ending is added:

• trappeopgang = a stairwell
• trappeopgangen = the stairwell

This is very normal in Danish. Where English often uses several words, Danish often prefers one combined noun.

Because -en is the definite article ending in Danish.

In English, you usually put the before the noun:

• the stairwell

In Danish, the noun usually gets the definite ending instead:

• trappeopgangen = the stairwell

So:

• en trappeopgang = a stairwell
• trappeopgangen = the stairwell

This is one of the most important differences between English and Danish nouns.

For the same reason: Danish usually marks definiteness by adding an ending to the noun.

• en vicevært = a caretaker / superintendent
• viceværten = the caretaker / superintendent

So English says:

• the caretaker

But Danish usually says:

• viceværten

without a separate word for the.

Vicevært is a common Danish word for a person who looks after a building or apartment block.

Depending on context, it can mean something like:

• caretaker
• superintendent
• janitor
• building manager

It does not always match any single English word perfectly. In housing contexts, caretaker or superintendent is often the best translation.

Because ren agrees with the noun trappeopgangen, which is a common-gender singular noun.

The adjective ren changes form depending on grammar:

• en ren trappeopgang = a clean stairwell
• et rent rum = a clean room
• rene trapper = clean stairs

Here, the subject is:

• trappeopgangen = the stairwell

Since trappeopgang is a common-gender noun, the adjective form is ren.

So:

• Trappeopgangen er ren = The stairwell is clean.

Because venligt is being used as an adverb, not as an adjective.

Compare:

• en venlig vicevært = a friendly caretaker
  Here venlig describes a noun, so it is an adjective.

• viceværten hilser venligt = the caretaker greets people kindly / in a friendly way
  Here venligt describes how he greets, so it is an adverb.

In Danish, adverbs are often formed from the adjective by adding -t:

• venlig = friendly
• venligt = kindly / in a friendly way

Because it is modifying the verb and Danish commonly places this kind of adverb after the verb.

So:

• hilser venligt = greets kindly / greets in a friendly way

This is very natural Danish word order.

You could sometimes move elements around for emphasis, but the sentence as given is the normal, neutral order.

Om morgenen is the usual Danish way to say in the morning.

Breakdown:

• om = in / during / around, depending on context
• morgenen = the morning

So literally it is something like during the morning, but in normal English we say in the morning.

This pattern is very common for times of day:

• om morgenen = in the morning
• om aftenen = in the evening
• om natten = at night / in the night

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

In the first clause:

• Trappeopgangen = position 1
• er = position 2
• ren = rest of the clause

In the second clause:

• viceværten = position 1
• hilser = position 2
• venligt om morgenen = rest

This verb-second pattern is a central feature of Danish grammar.

Yes. That is also correct.

Because Danish is a V2 language, if you move om morgenen to the front, the verb still stays in second position:

• Om morgenen = position 1
• hilser = position 2
• viceværten = then comes after the verb

So:

• Viceværten hilser venligt om morgenen = neutral order
• Om morgenen hilser viceværten venligt = more emphasis on the time

Both are grammatical.

A rough guide for English speakers is:

• vice sounds roughly like VEE-se
• vært has a vowel that does not exist in English; æ is somewhat like the vowel in cat, but said differently and often more open
• -en is the definite ending

Very roughly: VEE-se-vairt-en
But that is only approximate.

A few useful points:

• Danish v is usually like English v
• c in vice is pronounced like s
• æ is an important Danish vowel you will need to get used to
• the r in Danish is not pronounced like a strong English r

If you want to sound natural, it is best to listen to native audio, because Danish pronunciation is often less phonetic than the spelling suggests.

Yes, it is completely normal.

It is a simple sentence with:

• a definite subject: trappeopgangen
• the verb er
• a predicate adjective: ren

This is the standard way to say that something is clean in Danish.

So the pattern is:

• Noun + er + adjective

For example:

• Lejligheden er stor = The apartment is big
• Gården er stille = The courtyard is quiet
• Trappeopgangen er ren = The stairwell is clean

Because the sentence is talking about specific, identifiable things:

• the stairwell
• the caretaker

In a housing or building context, both are understood as known things, so Danish naturally uses the definite form.

If you made them indefinite, the meaning would change:

• En trappeopgang er ren = A stairwell is clean
• En vicevært hilser venligt om morgenen = A caretaker greets kindly in the morning

Those sound much more general or less tied to a specific situation. The original sentence sounds like it is describing a particular building.