Here Paul compares the number of the people of Israel to the number of grains of sand in the sea. AT: "too many to count" (See: [[rc://en/ta/man/translate/figs-simile]])
Paul uses the word "saved" in a spiritual sense. If God saves a person, it means that through believing in Jesus' death on the cross, God has forgiven him and rescued him from being punished for his sin. You can translate this in an active form. AT: "God will save" (See: [[rc://en/ta/man/translate/figs-activepassive]])