A prorogation is the period between two sessions of a legislative body.
When a legislature or parliament is prorogued, it is still constituted (that is, all members remain as members and a general election is not necessary), but all orders of the body (bills, motions , etc.) are expunged.
In the British and Canadian parliamentary systems, this is usually due to the completion of the agenda set forth in the Speech from the Throne. Legislatures and parliaments, once prorogued, remain in recess until summoned again by the Queen, Governor General, or Lieutenant Governor, and a new session is begun with a Speech from the Throne.