Death is the opposite of life. When God breathed into Adam the breath of life, he became a living soul. Of course, when Adam disobeyed God and took a bite of the forbidden fruit, he became a dying soul (Genesis 2:17). Here in Leviticus 20 there are 29 direct or indirect references to death. While chapter 19 was a focus upon the rules, chapter 20 is a focus on the consequences of breaking those rules: death.
In both testaments the Bible verifies the solemnly morbid warning of God: "The soul that sins, it shall die" (Ezekiel 18:20) & "The wages of sin is death" (Romans 6:23). Death is a sure thing. It is also a constant possibility. Every breath that I take is potentially my last one. Death is our enemy. Death is a dark and mysterious door... a door that most of us willingly avoid rather vigorously. Yet, death is a universal experience... an occasion well worth our discussion.
The specific capital crimes listed here are as follows: offering children as human sacrifices, occultism, cursing one's parents, adultery, incest, homosexuality, bestiality and I'm not sure what to call the only remaining fatal infraction in this particular list. Anyway, by stoning, by fire or by whatever other means, God ordained death as the just consequence for all such transgressions. But, those legislations were directed at individuals. However, God's justice is not just vindicated upon individual sinners. Corporate, national, geographic and racial consequences are also guaranteed. Distinctively, in this context, the nation of Israel was threatened with national exile if they ignored God's mandates (Leviticus 20:22-23). In a sense, rebellion would bring the death of the nation.