Peace is spoken of as if it were a place. This can be restated to remove the abstract noun "peace." Alternate translation: "I will be peaceful when I lie down and sleep" or "I will not be afraid of danger when I lie down and sleep" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-abstractnouns]])
The words "safe" and "secure" mean basically the same thing and emphasize complete safety. Alternate translation: "make me completely safe" (See: [[rc://en/ta/man/translate/figs-doublet]])