Teaterplakaten henger på veggen ved inngangen.

The ending -en is the definite singular article for a masculine noun.

• teaterplakat = a theatre poster
• teaterplakaten = the theatre poster

So teaterplakaten means the specific theatre poster, not just any poster.

Norwegian very often puts two nouns together into one compound noun:

• teater (theatre) + plakat (poster) → teaterplakat (theatre poster)
• Then you add the definite ending: teaterplakaten = the theatre poster

Writing it as two words (teater plakat) would be wrong in standard Norwegian. The meaning is bundled into one concept.

Plakat is a masculine noun:

• en plakat – plakaten
• en teaterplakat – teaterplakaten

Because it’s masculine, the definite singular ending is -en, which shows up at the end of the whole compound: teaterplakat + en → teaterplakaten.

In Norwegian, henger already includes the meaning is hanging. You don’t say er henger.

• henger = is hanging / hangs
• Teaterplakaten henger … = The theatre poster is hanging …

You only use er with an adjective or noun complement, like:

• Plakaten er stor – The poster is big

• henger (intransitive): describes the state – something is hanging.
  
  • Plakaten henger på veggen. – The poster is hanging on the wall.
• henger opp (transitive + particle): describes the action of hanging something up.
  
  • Jeg henger opp plakaten. – I am hanging up the poster.

In your sentence we describe where the poster is, so henger is correct.

På is used for being on a surface, including vertical surfaces like walls:

• på veggen – on the wall
• på bordet – on the table

Using i veggen (in the wall) would mean inside the wall (e.g. en ledning i veggen – a wire in the wall), which is a different meaning.

Again, -en marks the definite form:

• en vegg = a wall
• veggen = the wall

In this sentence, we are talking about a specific, known wall: the wall by the entrance. So Norwegian uses the definite form veggen, just like English uses the.

Both can often be translated as near the entrance, but there is a nuance:

• ved inngangen: very close, essentially by / at the entrance area; you expect it to be right there.
• nær inngangen: somewhat near, but not necessarily right at the door; it’s more general.

In the sentence, ved inngangen suggests the poster is located right by the entrance.

Inngang is a masculine noun:

• en inngang – an entrance
• inngangen – the entrance

We are talking about a specific, identifiable entrance (e.g., the entrance to the theatre), so Norwegian uses the definite form inngangen, just like English uses the entrance.

Yes, you can say:

• På veggen ved inngangen henger teaterplakaten.

Two things change:

1. The focus: now you emphasize the location first.
2. The word order: when an adverbial (like På veggen ved inngangen) comes first, the verb henger must still be in second position, so the subject teaterplakaten moves after the verb.

Both versions are grammatically correct; the difference is mainly emphasis.

You could say:

• Det henger en teaterplakat på veggen ved inngangen.

Differences:

• Det henger … is an existential construction (introducing something): There is … hanging …
• en teaterplakat = a theatre poster (indefinite, not known before)
• The original sentence has Teaterplakaten henger … = The theatre poster is hanging …, referring to a specific, known poster.

So the grammar changes because the meaning shifts from introducing a poster to locating a known poster.

In a simplified phonetic form (Bokmål, standard East Norwegian):

• teaterplakaten ≈ te-AH-ter-pla-KAH-ten

Stress:

• Primary stress on a in -plakaten: plakaten
• Secondary stress on a in teater: teater

So you hear something like:

• teAterplaKAten

The word is long, but it’s just teater + plakat + -en said smoothly together.