The acronym CEU stands for Continuing Education Unit. According to The International Association for Continuing Education & Training (IACET):

"One Continuing Education Unit (CEU) is defined as 10 contact hours (1 hour = 60 minutes) of participation in an organized continuing education experience under responsible sponsorship, capable direction, and qualified instruction. The primary purpose of the CEU is to provide a permanent record of the individuals who have completed one or more non-credit educational experiences."