The word "Israel" represents the people of Israel. Alternate translation: "People of Israel, trust in Yahweh" (See: [[rc://en/ta/man/translate/figs-metonymy]])
The writer speaks of Yahweh as if he were a shield because he protects his people as a shield would protect them from harm. Alternate translation: "the one who helps you and protects you" (See: [[rc://en/ta/man/translate/figs-metaphor]])