rules and dice mechanism

[shaharhada]

What is the meaning of rules and dice mechanics in the paragraph:
"What is a Tabletop Role Playing Game?
A Tabletop Role Playing Game is a sort of shared story, facilitated by a 'Game Master' who tells the story, allowing the other players to act as individual characters in the world. There are rules and dice mechanics to separate this from a freeform shared story, but instead establish this as both a shared story AND game..."
From the link: https://ava-portal-files.s3.us-west...ea5987f6cac20fb4cfd7774f112779092e6cc45310770

 

[USAFRet]

"Rules" - There are rules for the game.

"dice mechanics" - different games may have different dice. 6 sided, 12 sided, 20 sided...each of which has different "mechanics".