What does Mark chapter 7 verses 14-23 mean?

20And he said, That which cometh out of the man, that defileth the man. 21For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, 22Thefts, covetousness, wickedness, deceit, lasciviousness, an evil eye, blasphemy, pride, foolishness: 23All these evil things come from within, and defile the man.