If you have up-to-date referees, give their details on your CV. Otherwise, write: 'References will be provided on request'. A former employer is most often used as a reference. The reference supports your application and describes you and your ability to work.
Letters of recommendation are needed and can help you. Bring them when you attend the interview. They should be written by a former boss, team leader or HR officer. If you don't have work experience, you can provide a letter of recommendation from a teacher or a sports leader.