At the beginning of Act 4, Time, a winged figure with an hourglass, appears on stage. Time is an allegory. (An allegory is a kind of extended metaphor that’s weaved throughout a poem or play in which objects, persons, and actions stand for another meaning. In this case, Time stands for, well, time.) Because Time announces that the play has fast-forwarded sixteen years into the future and tells us that the setting has changed from Sicily to Bohemia, where Perdita has grown up, Time is also acting the part of a Chorus (kind of like a narrator).
During his speech, Time apologizes to the audience for all of this: “Impute it not a crime / To me or my swift passage, that I slide / O'er sixteen years and leave the growth untried / Of that wide gap” (4.1.1). Translation: “Don’t be mad that the play has skipped ahead sixteen years.” Why is Time apologizing? Well, flash forwards and major setting changes were a big no-no on the English stage in Shakespeare’s day because they disregarded the “classical unities” (of time, place, and action), a set of literary rules that said all plays should have the following features: 1) the action should take place within a 24 hour time span; 2) the action should take place in one geographical place/setting; 3) the play should have one main plot and no sub-plots. The Winter’s Tale pretty clearly breaks all of these rules (as did many other Shakespeare plays).