Bhai - Brother
Beej - Second day of the month
Yamunaji the divine form of river Yamuna had invited her brother Yama Raj for a meal at her home. As Yama is always busy handling the affairs of Yamapuri, he couldn't find time to go to her sister's house but on one occasion on Kartik Sud Beej, he went to his sister's house for a meal. Yamunaji was very pleased to see her brother and welcomed him by placing a tilak on his forehead and performed an Aarti to show her affection towards her brother. She prayed for his protection and then served him a great meal. Yama Raj was very pleased with his sister and he offered her a wish whereby she can ask him for anything that she would like. She requested that on this day any brother who would accept an invitation and go to his sister's house for a meal would find eternal happiness and would not face any difficulties in his life.
So this day on Kartik Sud Beej came to be known as Bhai Beej. Brothers or cousin brothers go to their sisters' houses on this day and sisters prepare a loving meal for them. Before having a meal the sister would place a tilak on his forehead and pray for his wellbeing. She would also place a sweet in his mouth to welcome him to her house. After the meal a brother would give his sister money or gifts to show that he too loves and cares for her sister. So Bhai Beej, the second day of the Hindu New Year, is for strengthening the bond of affection between brothers and sisters.