Whoso is keeping the command is keeping his soul, Whoso is despising His ways dieth.
An even more literal translation of this passage is this:
Shamar [guarding] mitzvah [commandment] shamar [guarding] nepheshu [his soul] botzah [despising] derekiv [his ways] yevamot [he will die]
He who guards the commandment guards his soul. Despise His Ways, he will die.
The message is simple: guard the commandment and you will guard your soul. If you despise His Ways then you will die. We find an interesting twist in the meaning if we include our understanding of the work of Messiah Yeshua:
He who guards the commandment guards his soul. Despise His Ways, He will die.
And indeed He did. The prophet Isaiah spoke truly:
All of us like sheep have gone astray, Each of us has turned to his own way; But the LORD has caused the iniquity of us all To fall on Him. (Isaiah 53:6)
To Him who died in my place, who "bore [my] sins in His body on the cross, so that [I] might die to sin and live to righteousness; for by His wounds [I] am healed" (1 Peter 2:24)... to Him be the glory and honor and praise forever. Amen.