What does 1 Samuel 17:37 mean?

David added, 'The Lord who saved me from the lion and the bear will save me from this Philistine.' Saul said to David, 'Go ahead, and may the Lord be with you.' 1 Samuel 17:37 - Modern Text Bible

(David’s confidence comes from his trust in God, not just his own skills. Saul finally agrees to let him try.)