Question

what is adjective?try to explain the sentence sita is a clever girl

Answer 1

A word used with a noun to describe or point out , the person, animal, place or thing which the noun names, or to tell the number or quantity, is called an adjective
sita is a clever girl( in this it is explained about that she is a girl who is clever)
hope you like it and it helps

Answer 2

adjectives are words that describe or modify another person or thing in the sentence. when they describe nouns or pronouns , adjectives typically ans the following question :-
1. what kind?
2. which one ?
3. how many ?
adjectives are usually placed before noun. adjectives may also follow the noun they describe like smitherman , cold and achy , etc. adjectives r often recognizable by their suffixes like -ous, -ful, -ish , -able . 

                 
                                                      hope it helps u