What is an adjective?

What is an adjective and how do I use them in English? Please help me.

Adjective is a word that describes a noun or pronoun. In the phrase ‘black hat’, ‘black’ is an adjective and in the sentence `It makes her happy’, ‘happy’ is an adjective.

Thank you Milanya. That was helpful. Acha is having a difficulty with her English grammar.
Is there an adjective in above line? And do I need to put a before difficulty?

English is an adjective. It describes the noun grammar.


Thank you very much.