The Curia is a democratically elected group of officials, governing the Tollan people. The Curia can make vital decisions for the future of their people but they hold little power. For example, they don't have the power to enter into a contract with the Goa'uld. The transcripts of all the meetings of the Curia are recorded in a publicly accessible place, so all Tollans can read their discussions.
Up until the destruction of the Tollan people by the Goa'uld, the leader of the Curia was High Chancellor Travell.