...you are aware that "dice" is already the plural form of die, right?
Semantics aside, many tabletop RPG's utilize multi-faced dice beyond the traditional d6 (the 6-faced die) in order to provide more precise range of considered numbers for outcomes.
With a d20, you have 5% chance of getting any particular number... & many skill checks in D&D have a certain "difficult class" (or DC) to reach, after any modifiers are applied. A DC of 10 would give a player 50-50 chance of success (although, players may "take 10" on many mundane tasks where time isn't a critical factor). Anything with a DC of 20 or higher would require the player to have a modifier to reach it (although D&D will give players a "critical success" whenever you roll a natural 20).
Other dice, like d4, d6, d8, d10 & d12 are more commonly used for dealing damage. d100 (commonly noted as d% & is generally handled with 2d10) are typically used with mass lists of randomness.
Hope this helps!