What is the word pronoun mean?

A pronoun is a Word that takes the place of a noun in a sentence in order to make the Words less repititious and to make sentences flow more smoothly.

Example:

Sandy got a new puppy. Sandy's new puppy got Sandy'snew puppy's paws in the mud then tracked Sandy's new puppy's muddy footprints all over Sandy's kitchen floor.

OR

Sandy got a new puppy. Her new puppy got his paws in the mud then tracked his muddy footprints all over herkitchen floor.