The words "whole country" are a metaphor for the people who live in the country and a generalization that refers to a great number of people, not to every single person. AT: "Many people from Judea and Jerusalem" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-hyperbole]])
# They were baptized by him ... confessing their sins
They did these things at the same time. The people were baptized because they repented of their sins. AT: "When they repented of their sins, John baptized them in the Jordan River"
# he was eating locusts and wild honey
Locusts and wild honey are two kinds of foods that John customarily ate while he lived in the wilderness. This does not mean that John was actually eating these foods while he was baptizing people.