Klatregrepet er grønt.

Because Norwegian usually writes compound nouns as a single word.

Here, klatregrepet comes from:

• klatre = climb
• grep = grip, hold

So the basic noun is klatregrep = climbing hold.

This is very common in Norwegian. Where English often uses two words, Norwegian often uses one compound word.

It is built into the end of the noun.

The base form is:

• et klatregrep = a climbing hold

The definite form is:

• klatregrepet = the climbing hold

The ending -et is the neuter singular definite ending. So Norwegian often expresses the by adding an ending to the noun instead of using a separate word.

Klatregrep is a neuter noun, so its indefinite form is et klatregrep.

We know this because in Norwegian compounds, the last part usually decides the gender and inflection. The last part here is grep, and grep is neuter:

• et grep
• grepet

So the compound follows the same pattern:

• et klatregrep
• klatregrepet

Because the noun it refers to is neuter singular.

In Norwegian, adjectives agree with the noun in gender and number. With grønn, the main forms are:

• grønn for common gender singular
• grønt for neuter singular
• grønne for plural

So:

• Bilen er grønn = the car is green
• Huset er grønt = the house is green
• Bilene er grønne = the cars are green

Since klatregrepet is neuter singular, grønt is the correct form.

Because grønt here is a predicative adjective: it comes after er and describes the subject.

Predicative adjectives in Norwegian agree with gender and number, but not with definiteness.

So:

• det grønne klatregrepet = the green climbing hold
  
  • adjective before the noun
  • definite form grønne

but:

• klatregrepet er grønt = the climbing hold is green
  
  • adjective after er
  • neuter singular form grønt

This is a very common pattern in Norwegian.

You would say:

• Et klatregrep er grønt.

That is the same sentence pattern, but now the noun is indefinite:

• et klatregrep = a climbing hold
• er grønt = is green

You would say:

• Klatregrepene er grønne.

Here both the noun and the adjective change:

• klatregrepene = the climbing holds
• grønne = green, plural form

So the singular/plural contrast is:

• Klatregrepet er grønt. = the climbing hold is green
• Klatregrepene er grønne. = the climbing holds are green

Then you need the adjective before the noun:

• det grønne klatregrepet = the green climbing hold

Compare:

• Klatregrepet er grønt. = The climbing hold is green.
• Det grønne klatregrepet = the green climbing hold

So the first is a full sentence, while the second is just a noun phrase.

Not really. It comes from the verb å klatre, but inside klatregrep it is simply the first part of a compound noun.

So in this sentence, the whole word klatregrepet is a noun, and klatre is not being conjugated or used as a verb by itself.

The tricky part is the vowel ø. It does not have an exact English equivalent.

A rough guide:

• grønt is approximately /ɡrœnt/
• the ø is somewhat like the vowel in bird, but with rounded lips
• the final t is pronounced

A rough English-style approximation might be grurnt, but that is only approximate.