Adjectives describe a person, place or thing. a, an and the are known as articles examples would be the boy, an apple, a picture.
So now that adjectives have been explained seems pretty simple so far so of course lets complicate it just a little there are more to adjectives than the articles speaking in particular of Adjective Clause this is where a group of word has a subject and verb, here is an exmaple of an adjective clause: My dad, who is my mom’s husband was in the military.