Once you refer your friend to Abyss you will earn a reward from it, that is a direct referral. The indirect referral is the reward you will earn if the one you refer will also refer a friend to Abyss. To cut it short, direct referral is the one you directly refer to Abyss and the indirect referral is your down line referral of your friend (the one who refer you directly to join Abyss). Hope this will help you understand.