Free credits are play money chips. They hold no value but can be used in our casino to play for fun if you do not have a real money balance or the minimum bet amount required for a game.
Those credits are quite helpful for the ones who want to enjoy the games without spending money, they're helpful for the ones who love demo betting. I still believe that's a good option especially for the ones who just want to have some fun but don't have money at that moment.