Rock of my strength is a descriptive name of God found in a psalm. It simply points to God as the source of strength for endurance and protection from enemies. We can know Him in exactly those ways.
Rock of my strength in Hebrew:
Strong’s Concordance numbers: 6697, 5797
Bible reference: Ps. 62:7
On God my salvation and my glory rest;
The rock of my strength, my refuge is in God. (Psalm 62:7)
The NIV prefers the term “my mighty rock.”
Similar descriptive names for God in the Old Testament are God my strength and My stronghold.