The dice roller is more often than not used for dice rolls in roleplays. Sometimes in a game, you will have to roll to determine whether something happens or not. For example, in dungeons and dragons, you roll for initiative (to determine who goes first), you roll for attack (to determine if an attack hits or not) and you also roll for damage.
Next time, please use this thread for asking questions (if you are not introducing yourself at the same time, of course.): Site Questions & Information