1)
What is "mi'Kol Ra"?
1.
Bereishis Rabah (68:2): [Hashem will guard Yakov] from Esav and Lavan (refer to 121:1:3:2).
2.
Radak: People and wild animals.
3.
Malbim: It is all worldly evils that affect the body.
2)
What is the meaning of "Yishmor Es Nafshecha"?
1.
Bereishis Rabah (68:2): [Hashem will guard Yakov] from the angel of death (refer to 121:1:3:2).
2.
Radak: If illnesses come on you, it is to cleanse sins; He will guard that you not die from them.
3.
Malbim: He will guard your Nefesh from sin.