Epsom is a town in Surrey, just south of London, in southeast England. English speakers know it because of Epsom Downs, the racecourse on the hill above the town. Each year the Derby — one of the most famous horse races in Britain — is run there. British people say the race name like “Darby,” not “Der-bee.” The tidy school line is “a town famous for horse racing,” and that is the sense you need; though actually the same town also gave its name to Epsom salts, a bitter white salt first taken from springs there and later used in baths. In ordinary talk, if someone says they are “going to Epsom,” they may mean the town, the shops, or the races, depending on the day.