# to shine on those

"to give spiritual light to those"

# those who sit in darkness and in the shadow of death

Darkness can represent sin, separation from God, and the lack of spiritual truth. The shadow of death represents the threat of death. Alternate translation: "those who are in spiritual darkness and are in danger of dying" 

# to guide our feet into the path of peace

"to guide us into the path of peace" or "to teach us how to live at peace with God"