The Prologue, a character who doesnt appear in the rest of the play, comes on stage and tells us the general outlines of the plot.
Two houses of Verona, the Montagues and the Capulets, have been feuding for years. New fighting can erupt at any time. But the son and heir of the Montagues, Romeo, meets the daughter of the Capulets, Juliet, and they fall in love. Their love is forbidden, but they pursue it anyway, inviting parental condemnation and societal scorn. It is only the fact that they, faced with impossible choices, choose to kill themselves rather than go on, that makes it possible for the two houses to reconcile. Both houses are torn by grief, and they see the way out of their quarrel as a result of their mutual loss.
To come on stage.
Latin, literally they leave. Everyone leaves the stage.
The character leaves the stage.