What does Exodus 13:5 mean?

When the Lord brings you into the land He promised to your ancestors—the land of the Canaanites, Hittites, Amorites, Hivites, and Jebusites—a land flowing with milk and honey, you must celebrate this ceremony in this month every year. Exodus 13:5 - Modern Text Bible

(God is reminding them to keep this tradition when they reach the land He promised.)