Definition of 101 in English:

adjective

• 1Denoting an introductory course at college or university in the subject specified.

  ‘The Saturday and Sunday 101 classes start at 3pm’

  ‘Signing up for a Stripper 101 class can be a real edge.’

  1. 1.1informal Denoting the elementary or basic facts associated with the field or subject specified.
     ‘stuff that you should learn in hacking 101’