Adjective - describing word
Pronoun - words that substitute for nouns
Superlative - describing the highest kind 

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ADJECTIVE is a word modifies or describe a noun or a pronoun.
example: pretty, handsome, bad, good, big, small

PRONOUN is a word  that take place of a noun.
example: she is pretty, he is handsome, we are good.

SUPERLATIVE is a highest degrees comparison of adjectives
example: she is prettiest among them,
               he is the most handsome in our classroom.

--(^_^)---hope it can help.......