Hi can someone please explain what "medium" means in literature? how does a medium affect a story? and what are the connections between a medium and theme

Read the excerpt from cristina garcia’s dreaming in cuban. i don’t really want to talk about my father but i end up telling minnie how he used to take me horseback riding on our ranch, strapping me in his saddle with a leather seat belt he designed just for me. dad’s family owned casinos in cuba, and had one of the largest ranches on the island. there were beef cattle and dairy cows, horses, pigs, goats, and lambs. dad fed them molasses to fatten them, and gave the chickens corn and sorghum until they laid vermilion eggs, rich with vitamins. he took me on an overnight inspection once. we camped out under a sapodilla tree and listened to the pygmy owls with their old women’s voices. my father knew i understood more than i could say. he told me stories about cuba after columbus came. he said that the spaniards wiped out more indians with smallpox than with muskets. how does the structure of the excerpt add meaning to the passage? it includes historical information about the spaniards and indians to indicate the work is nonfiction. it describes the setting of the ranch owned by pilar’s cuban grandparents to explain family values. it uses several narrators to share their points of view about past and present life in cuba. it manipulates the chronological order of events to reveal the close relationship between pilar and her father.