Adjectives refer to nouns in two ways: either as an attribute or as a predicate.
Qualifies the noun, to describe, without any assertion about it. The attributive is an adherent description.
The Position: ὁ πιστός δοῦλος or ὁ πιστός ὁ δοῦλος
Note: the adjective comes immediately after the article.
Makes an assertion about the noun. The predicate is an additional statement.
The Position: ὁ δοῦλος πιστός or πιστός ὁ δοῦλος
Note: the adjective does not come immediately after the article but either precedes the article or follows the noun.
The Adjective may also be used as a noun: ὁ ἁγαθός “the good man”.