The two olive trees and the two lampstands symbolize these people, but they are not literally the people. Alternate translation: "The two olive trees and the two lampstands that have stood before the Lord of the earth represent these witnesses" (See: [[rc://en/ta/man/translate/writing-symlanguage]])
John expects his readers to know about them because many years earlier another prophet had written about them. Alternate translation: "the two olive trees and the two lampstands, told about in scripture, that" (See: [[rc://en/ta/man/translate/figs-explicit]])