Introduction to pronoun
The following sentence does not have any pronouns, so it seems repetitive
Karan drove Karan's car to Karan's workplace, where Karan met Karan's boss.
Using pronoun the above sentence changes to..
Karan drove his car to his workplace, where he met his boss.
By using pronouns to stand for Karan, we replace four Karan with he or his.
Note; Generally, readers do not notice the repetition of pronouns as much as they notice the repetition of nouns, so the sentence seems less repetitive.
Examples of pronouns are I, me, he, she, herself, you, it, that, they, each, few, many, who, whoever, whose, someone, everybody, etc