Learn Turkish: Bilet çok pahalı değil. - The ticket is not very expensive.

In this sentence, it means 'very'. When çok is placed right before an adjective like pahalı (expensive), it translates to 'very'. If it were used before a noun or an action verb, it would mean 'many', 'much', or 'a lot'.

Where do degree words like çok or biraz go in a Turkish sentence?

Just like in English, they go directly before the adjective they are describing. To say 'very expensive', you simply say çok pahalı. If you wanted to say 'a little expensive', you would just swap it for biraz pahalı.

Where is the word for 'is' in this sentence?

Turkish doesn't have a separate word for 'is' (or 'am' / 'are') for the third person in simple descriptive sentences like this. Stating the subject (bilet) followed by the description (çok pahalı) and the negative word (değil) is all you need to build the sentence.

Why do we use değil to mean 'not' here, instead of yok?

değil is the specific word used to negate adjectives and nouns—it is the Turkish equivalent of 'is not' or 'are not'. yok is used to say 'there is not' or to show that something doesn't exist. Since we are describing what the ticket is not, we must use değil.