What do the teacher mean by central idea? ?

The teacher means your idea of the story  like what the story is really about what you want the story to be.

explanation: yee yee

in this text, paine use the word “ye” several times in order to  capture  the  attention of the colonists who   haven't understand the   importance and urgency of his cause. the word "ye" that is the plural of   "thou" is used to call the colonists attention and make the fight for the cause.