Be holy, because God is. Various laws related to fairness, and loving and honoring your neighbor.
Punishment for gross sins: Child sacrifice, sorcery, cursing parents, adultery, incest, homosexuality, bestiality all call for the death penalty.
Verses 24-26 gives a clear reason for the food laws: to show Israel is meant to be morally distinct from other nations around them.
How this is about Jesus
Because of the resurrection, I believe these sins now warrant excommunication, rather than death. John 8:1-11 is one proof of this.
Sins this reveals
These chapters relate mostly to Ten Commandments 5-8.