Adjectives describe the quality/features/quantity of the noun in the sentence. Adjectives give additional information about the noun in the sentence. It can modify the noun to denote quality, to indicate its quantity, order or extent.
Her dress was beautiful.
She had a beautiful dress in her closet.
An adjective not only describes a noun but can also act as a complementing verb. Adjectives in the first position, before the noun is called an attributive adjective. Adjectives, when used after the noun as a verb, is called a predicative adjective.
1. The excited child ran towards us. ---> The adjective "excited" is used before the noun(child).
2. The child was excited and ran towards us. ---> The adjective "excited" is used after the noun(child), as a verb.
In the first sentence, "excited" is used attributively (used before the noun) and in the second, predicatively (used after the noun, as a verb).
Usually, adjectives with the prefix a- are used only after the verb.
  • awake
  • asleep
  • aboard
  • alive
  • alone etc.
My brother was asleep.
Thank god that we're alive now!
Also, adjectives which usually describe feelings appear after the verb.
  • glad
  • ready
  • sure
  • sorry
  • upset etc.
I was glad that I could help.
He was sorry about my friend's accident.