Adjectives modify nouns and answer the adjectival questions. Adjectives can be attributive adjectives, predicate adjectives, or substantival adjectives.
An adjective in attributive position is “the good word”.
An adjective in predicate position is “the word is good“.
Again, we see adjectives in both attributive and predicate position. They can also be substantival. The article is the key. When an adjective is articular, it is attributive; when anarthrous, it is a predicate adjective and will be the complement of a linking verb. Study chapter 9 in BBG and syntax principle 7.
Begin your study of adjectives by studying the the first four pages here. Be sure to know the difference between an attributive, predicate, and substantival adjectives in both English and Hebrew. They are very similar.