"He alone is my rock and my salvation; he is my fortress, I will never be shaken."
To me this verse means that God is always there with us and no matter what happens to us, we will not be shaken because God is there. He is by our side 24/7.
Many of us try and work to get money and riches and fame, but when that all crashes and fails, we still have God's protection. As long as He is our "rock" we will not be shaken.