Turn right at the end of the street.

In the sentence 'Turn right at the end of the street', the word 'right' modifies the verb 'turn', indicating the direction in which to turn. Words that modify verbs are adverbs. Here 'right' functions as an adverb of direction. While 'right' can be used as a noun or adjective in other contexts, in this sentence it modifies the verb 'turn' and therefore is an adverb.