Many, many things
As a liberal arts major, of course, the world is your oyster and you can consider a multitude of careers.
Among the jobs you can consider are: advertising executive, analyst, archivist, broadcaster, campaign worker, consultant, congressional aide, editor, foreign service officer, foundation staffer, information specialist, intelligence agent, journalist, legal assistant, lobbyist, personnel manager, public relations staffer, researcher, teacher . . . the list can be almost endless.
More specifically, though, with your degree in history you can be an educator, researcher, communicator or editor, information manager, advocate, or even a businessperson.
Here is a brief list of the career opportunities available to the undergraduate history major, compiled in 2006. This list is based on a very useful pamphlet, Careers for Students of History, written by Barbara J. Howe and jointly published by the American Historical Association and the National Council on Public History in 1989. While this online miniguide is based on this pamphlet (now out of print), with appropriate paraphrases from its text, it discusses also some of the new opportunities that became available to the history major in the recent past.