You will write three different essays explaining three reasons in each one why the use of social media harms or benefits the country. Your three points can be restricted to three harms, or restricted to three benefits. Approaches will vary. Just stay on the topic; follow your thesis statement; and supply LOTS of examples to prove your point.
First essay’s three reasons are harms, second essay’s three reasons are benefits, third essay three reasons can be harms/benefits, but different than the other one. Thesis statement is a requirement with showing the three reasons for each essay.