Afgangshallen er stor.

Because -en is the definite article for many common-gender Danish nouns. It means the.

So:

• en afgangshal = a departure hall
• afgangshallen = the departure hall

Unlike English, Danish usually adds the definite article to the end of the noun instead of putting a separate word in front.

It is a compound noun:

• afgang = departure
• hal = hall

Together, afgangshal means departure hall, and afgangshallen means the departure hall.

Danish uses compound nouns very often, much like German.

Because afgangshallen is a common-gender noun, not a neuter noun.

In Danish, adjectives often agree with the noun:

• common gender singular: stor
• neuter singular: stort
• plural / definite adjective use: often store

So:

• en stor hal = a big hall
• et stort hus = a big house

Since hal is common gender (en hal), the sentence uses stor.

In this sentence, the noun itself is already definite because of -en in afgangshallen.

Danish often marks definiteness on the noun itself:

• hallen = the hall

So you do not need a separate the before the noun.

Also, this sentence is using the adjective after the verb er (is), so the pattern is simply:

• Noun + er + adjective

Example:

• Hallen er stor = The hall is big

Er means is / are / am as a form of the verb at være (to be).

Examples:

• jeg er = I am
• du er = you are
• han er = he is
• hallen er stor = the hall is big

In the present tense, er is used with all persons.

Yes. This is standard Danish word order for a simple statement:

• Afgangshallen = subject
• er = verb
• stor = adjective/predicative complement

So the structure is:

• Subject + verb + adjective

This is very similar to English:

• The departure hall is big.

You would say:

• en stor afgangshal

Notice two things:

1. The noun is now indefinite:
   • en afgangshal = a departure hall
2. The adjective comes before the noun:
   • en stor afgangshal = a big departure hall

Compare:

• Afgangshallen er stor. = The departure hall is big.
• en stor afgangshal = a big departure hall

Because Danish uses different patterns depending on whether the adjective is before the noun or after the verb.

In your sentence, the adjective is after er:

• Afgangshallen er stor.

Here, you do not use den or the -e adjective ending.

But if the adjective comes before a definite noun, then Danish usually uses double definiteness:

• den store afgangshal = the big departure hall

So compare:

• Afgangshallen er stor. = The departure hall is big.
• Den store afgangshal = The big departure hall

A rough English-friendly guide is:

• afgangshallen ≈ AHF-gangs-hal-en
• er ≈ a very short air / uh sound, often weak
• stor ≈ stoh with a Danish r

A few pronunciation notes:

• Danish g can sound softer than English in some positions.
• The r in Danish is not usually pronounced like a strong English r.
• Unstressed endings like -en are often pronounced quite lightly.

If you want to sound natural, listening to native audio is especially helpful with Danish pronunciation.

Mostly, stor means big / large, often for physical size, but it can also be used more broadly depending on context.

Examples:

• Huset er stort. = The house is big.
• En stor by. = A big city.
• Et stort problem. = A big problem.

In Afgangshallen er stor, the most natural meaning is physical size: the departure hall is large.

Yes. Hallen er stor means The hall is big.

That is a more general sentence.
Afgangshallen er stor is more specific, because it names the type of hall: the departure hall.

So:

• hallen = the hall
• afgangshallen = the departure hall

The dictionary form is usually the indefinite singular noun:

• en afgangshal

From that you can build other forms, for example:

• en afgangshal = a departure hall
• afgangshallen = the departure hall
• afgangshaller = departure halls
• afgangshallerne = the departure halls

Looking up the indefinite singular form is the normal way to find nouns in a dictionary.

Not always. It is a perfectly understandable and natural compound, but in real life the exact word can depend on context, airport signage, or speaker preference.

For example, people might also refer to related areas with other terms depending on what they mean exactly. But afgangshal clearly means departure hall, and Afgangshallen er stor is a good, natural Danish sentence.