You have never had hands on experience with Business Rule Framework? Not to worry, you can learn by playing the game Rock, Paper, Scissors. All you need is access to a SAP ECC or S/4 HANA system where Business Rule Framework activated and you have full authorisation associated to the transaction code BRF+.
Then simply sign up to receive daily emails that include all the instructions. You get acquainted with all the core functionality and terminology while you are building the game.