A more thorough explanation:

A malefaction is an evil deed or a crime. It is something that someone does that is wrong and against the law. For example, stealing, hurting someone, or lying to the police are all malefactions.

The word comes from the Latin word "malefacere" which means "to do evil". It is an old-fashioned word that is not used very often today.

Example: John was arrested for his malefaction of robbing a bank. This means that John did something wrong by stealing money from a bank, which is a crime.