A Dice Pool system is a mechanism whereby the player rolls a number of dice based on the character's stats and the task at hand. A character with a relevant stat of 4, for example, will roll four dice while a character with a relevant stat of 2 trying the same task will roll only two dice. The resulting dice are either summed or checked against a threshold to see if an action is successful. The difficulty of the task is usually set as a required minimum total of the dice rolled, or number of successes required.
The dice are usually the same type, i.e., all d6 or d10. The number of dice available for a given task will change as the character progresses in levels/skills.