Not Legal Advice: Sources suggest that if Chapter 5-17 is listed, this means you were administratively discharged because of a physical or mental condition that impaired your ability to successfully perform your duties.
Chapter 5-17 covers physical and mental conditions that don't rise to the level of medical disorders, but still impair a soldier's ability to effectively perform his duties, such as impaired emotion control, thinking and perception, as well as claustrophobia, chronic air or sea sickness, dyslexia and sleepwalking.
Prior to receiving a 5-17 discharge, the Army provides you with counseling and rehabilitation in the hope of keeping you enlisted. If you've been in the service for at least six years, you're entitled to challenge the proposed discharge at a hearing before the Administrative Separation Board.
Learn more about active duty enlisted administrative separations at Ansbach.army.mil.