Bowlinghallen er fuld i aften.

Because Danish usually writes compound nouns as one word.

Here, bowlinghallen is built from:

• bowling = bowling
• hal = hall / sports hall
• -en = the definite ending

So the basic noun is bowlinghal, and bowlinghallen means the bowling hall / the bowling alley.

This is very normal in Danish. English often uses separate words where Danish prefers compounds.

The -en is the Danish way of saying the with many nouns.

So instead of putting a separate word before the noun, Danish often adds the definite article to the end:

• en hal = a hall
• hallen = the hall

Since bowlinghal is a compound noun, the definite ending still goes on the end:

• en bowlinghal = a bowling hall
• bowlinghallen = the bowling hall

That is why there is no separate word for the in the sentence.

Er is the present tense of at være (to be).

So:

• jeg er = I am
• du er = you are
• han/hun er = he/she is
• den er = it is

In this sentence, er links the subject bowlinghallen with the description fuld.

It works just like English is in a sentence such as The bowling alley is full tonight.

Because the adjective agrees with the noun, and bowlinghallen is singular and common gender.

Basic pattern:

• en-word singular: fuld
• et-word singular: fuldt
• plural: fulde

Examples:

• Hallen er fuld. = The hall is full.
• Huset er fuldt. = The house is full.
• Hallerne er fulde. = The halls are full.

Since hal is an en-word, the correct form here is fuld.

In this sentence, fuld often means something like:

• full
• packed
• crowded
• sometimes fully booked or no more space left, depending on context

So it does not have to mean physically filled to the top. It can simply mean there are a lot of people and no room left.

A useful extra note: fuld can also mean drunk in other contexts, but that is not what it means here.

I aften is a common Danish time expression meaning this evening / tonight.

It works as an adverbial phrase telling you when something is true.

Similar expressions are:

• i dag = today
• i morgen = tomorrow
• i nat = tonight / during the night

So in this sentence, i aften tells you that the bowling hall is full tonight.

Yes. That is completely natural.

Danish is a V2 language, which means the finite verb usually comes in the second position in main clauses.

So both of these are correct:

• Bowlinghallen er fuld i aften.
• I aften er bowlinghallen fuld.

The difference is mainly focus:

• Bowlinghallen er fuld i aften. → starts with the place/topic
• I aften er bowlinghallen fuld. → starts with the time, so tonight is more emphasized

No, Danish nouns are not normally capitalized.

It is capitalized here only because it is the first word of the sentence.

So in the middle of a sentence, you would normally write:

• Jeg tror, bowlinghallen er fuld i aften.

Unlike German, Danish does not capitalize all nouns.

It is a normal Danish-style compound, even though bowling itself is a loanword.

Danish often combines borrowed words with native Danish words. So:

• bowling
  • hal → bowlinghal

That is very common and sounds natural in modern Danish.

So even if part of the word originally came from English, the whole form bowlinghallen follows ordinary Danish grammar.

The structure is:

• Bowlinghallen = subject
• er = verb
• fuld = subject complement / predicate adjective
• i aften = time expression

So the pattern is basically:

subject + verb + description + time

That is a very common Danish sentence pattern, especially with er:

• Restauranten er lukket i dag.
• Biografen er travl i weekenden.
• Bowlinghallen er fuld i aften.