What does Deuteronomy 6:3 mean?

So listen up, Israel, and be careful to do what he says. If you do, things will go well for you, and you'll become a huge nation in a land overflowing with good things, just like the Lord, the God of your ancestors, promised you. Deuteronomy 6:3 - Modern Text Bible

(Moses connects obedience with blessing and growth, reminding them of God's promises.)