valley A low land.
valley of the shadow of death America.
thy rod and thy staff The scriptures. The rod is for correction and the staff is you're measured (Revelation 11:1)
The first half of this verse is in reference to the Edomites, but the second half is referring to the hopeful elect of Israel (only the Lords servants can have faith Hebrews 11)
This whole chapter is a good story on faith, and more so, keeping the faith until death