Adjectives describe nouns
Languages often times use adjectives to enrich the meaning of the language as they add further descriptors to nouns. Biblical Hebrew does the same, with adjectives making up about 5% of the words in the תנ״ך.
In many ways, adjectives in Hebrew look much like nouns. They appear with a gender and number, and can likewise be found in construct form as a part of a construct chain. (More on this below.) The big difference is that adjectives do not possess an inherent gender as nouns do, but rather change their gender to match the nouns they describe. The following paradigm makes this clear.