What are reach, sales promotion, sales prospects, and social media?

"Reach is the number of different target consumers who are exposed to a commercial at least once during a specific period, usually four weeks. Sales promotion consists of marketing events or sales efforts—not including advertising, personal selling, and public relations—that stimulate buying. Sales prospects are the companies and people who are most likely to buy a seller’s offerings. Social media is a relatively new marketing channel that includes platforms such as Facebook, Twitter, LinkedIn, Pinterest, and Instagram."