The "apple of your eye" refers to something that is valuable. Alternate translation: "Protect me as you would something most valuable and precious" (See: [[rc://en/ta/man/translate/figs-simile]])
David speaks of God's protection as if he were a bird protecting its young under its wings. Alternate translation: "Keep me safe as a mother bird protects her babies by gathering them under her wing" (See: [[rc://en/ta/man/translate/figs-metaphor]])