"Blessed are they who mourn, for they shall be comforted."
The Second Beatitude means that when someone commit a sin, they would often mourn over their mistakes because they had did something against God. But after they die they would be comfort by God because they know what they did wrong and is forgiven.
Christmas was coming soon and there was a new toy that everyone had. A boy really wants the toy but he knows that his family couldn’t afford it. One day he went over his best friend house and saw that his friend just got the new toy and since his best friend parents are divorce he got two of the toys. While his best friend went to the bathroom he put one of the toy in his book bag and his friend came back, he said he had to go home now. He knew that taking the toy was wrong but he really wanted it. The boy felt really guilty and mourn about the mistake that he did. He felt so bad that he return the toy back to his friend and apologize. The boy learned from his mistakes and was comforted by God at night, sleeping freely of guilt.