Pronoun is made up of two Words Pro and Noun.
Pro means in place of, in favour of, instead of,
as an alternative, for rather than, as a substitute for and noun means namin word.
When we create a paragraph, noun keeps appearing in it again and again.

 Noun does not like to speak in every sentence
Pronoun is used to prevent the same noun from recurring.
Proven is used in the sentence where there is no noun and even after noun in many places, it is used.

Hina saw a snake on the floor.This Snake (which) Hina (she) thought would hurt Hina (her), unless Hina (she) killed the snake with a stick. This stick Hina had in Hina's (her) hands.

In given paragraph the coloured words are pronoun.

Category of Pronoun

Personal pronoun

Personal is called personal. Because it mentions three types of person. The Frist person who is talking, and the second person to whom the Frist person is talking, the third person the Frist and the second person are talking about.
Rules related personal Pronoun

The sentence in which positivity, unity, happyness is shown and given pronoun is singular. Rule 231 (second, third, Frist) is used there.

Rule 123 (frist, second, third) is used in a sentence where negative, division is shown and pronoun is in plural form.

When Frist, second and third person are used in plural form in a sentence, the order of their pronoun is 123, even if there is positivity, negativity, division, happyness in the sentence.