The setting on a plot structure diagram tells B. when and where the story takes place.
The setting is everything that relates to the time of the story, location of the story, and even the weather of the story. Sometimes it can even be the geographic location or economy, for example is the setting rich or poor?
I forgot to attach this plot structure diagram on my last answer to your question, so please check the attached image for future reference.
According to Boccaccio, some people believed the sins of some to be the cause of the plague. They believed that God punished them for committing sins by giving them the plague