What does Exodus 13:4 mean?

When the Lord freed Israel from slavery (Exodus 1:11–14; 12:40–41), He commanded new beginning to the Hebrew calendar (Exodus 12:2). This great event happened during a Jewish month then called Abib, which would later be known as Nisan. This begins in late March or early April; the dates are tied to cycles of the moon and vary from year to year. Many details related to Passover predict the sacrificial ministry of Jesus Christ (1 Corinthians 5:7; Luke 22:1–8).

Here, the focus is on a transition from preparation to action. The people are now "going out:" they are leaving the place where they were cruelly enslaved for centuries (Genesis 15:13). Moses will follow this (Exodus 13:5) with more instructions about the Promised Land (Genesis 15:18–21). When they arrive, they are to celebrate both Passover and the Feast of Unleavened Bread (Exodus 13:10). These would help them remember what the Lord did on their behalf in Egypt (Exodus 13:8).