Latteren er høy.

Because Norwegian often marks definiteness at the end of the noun instead of using a separate word.

• latter = laughter
• latteren = the laughter

So -en is doing the job that the does in English.

Because latter is a common gender noun in Norwegian, not a neuter noun.

Its basic forms are:

• en latter = a laugh / a laughter
• latteren = the laugh / the laughter

If it were a neuter noun, the definite ending would usually be -et, but that is not the case here.

Because latteren is a singular common gender noun, and when an adjective comes after er, it agrees with the noun.

So:

• common gender singular: høy
• neuter singular: høyt
• plural: høye

That is why you get:

• Latteren er høy.

If the noun were neuter, you would expect høyt instead.

In Norwegian, høy is often used for loud sounds. So in sound-related contexts, høy does not just mean high in the English sense.

For example, Norwegian can use høy for:

• høy musikk = loud music
• høy lyd = loud sound
• Latteren er høy = The laughter is loud

So this is a vocabulary difference between English and Norwegian.

Er is the present tense of å være, which means to be.

So:

• å være = to be
• er = is / am / are depending on context

In this sentence, er simply means is.

This is the normal statement pattern in Norwegian:

• subject + verb + complement

So here:

• Latteren = subject
• er = verb
• høy = complement/adjective

It works very much like English The laughter is loud.

If you want to turn it into a yes/no question, Norwegian usually changes the order:

• Er latteren høy? = Is the laughter loud?

Usually not in this context.

Latteren refers to a specific laughter, or to the laughter that is being talked about.
Latter without the definite ending sounds more general or abstract.

Compare:

• Latteren er høy. = talking about a particular laughter
• Latter er viktig. = talking about laughter in general

So in your sentence, latteren is the natural choice.

Not exactly. When an adjective comes before a definite noun in Norwegian, the structure changes.

You would normally say:

• den høye latteren

Here you can see two things:

• the extra definite word den
• the adjective form høye

But in your original sentence, the adjective comes after er, so you use the predicative form:

• Latteren er høy.

So:

• den høye latteren = adjective before the noun
• latteren er høy = adjective after er

Høy can be tricky for English speakers.

A rough guide:

• it starts with h
• the vowel is like the Norwegian ø, which does not exist exactly in English
• then it glides into a sound like y

So it is not pronounced like English hoy in a fully English way, even though that is a rough spelling clue.

If you are learning pronunciation, ø is the sound to focus on most here.