Leviticus 1-7 specifies the various sacrifices that were acceptable to God. The following chapters (8-17) detail some of the specifics (when, how, why, etc.) regarding those offerings.
Holiness:
Leviticus 11:44 "I am the Lord your God; consecrate yourselves and be holy, because I am holy."
Leviticus 20:7-8 "Consecrate yourselves and be holy, because I am the Lord your God. Keep my decrees and follow them. I am the Lord, who makes you holy."
Day of Atonement:
Leviticus 16 describes the sacred Day of Atonement when "Atonement is to be made once a year for all the sins of the Israelites." (v. 34)