What does Exodus 12:47 mean?

For those following Israel's covenant relationship to the Lord (Genesis 17:10–14), observing Passover was not optional. The phrase "congregation of Israel" is used frequently in the Old Testament in relation to Israel. This is meant to emphasize the communal, family nature of God's chosen people (Deuteronomy 14:2). In a broad sense, it means every single person in Israel (Leviticus 4:13; Numbers 16:9). Those not native to the nation could still participate, if they complied with the covenant (Genesis 17:10–14; Exodus 12:43–45, 48).

"Keeping" the Passover means following the Lord's instructions (Exodus 12:21–28) for remembrance. God finished His work (Exodus 3:19–20) of breaking the hold of Egyptian slavery (Exodus 1:11–14) over Israel using a terrible plague (Exodus 11:4–6). Those who followed His commands that night were spared (Exodus 12:12–13) as judgment would "pass over" their homes. Israel was commanded to remember this for all time (Exodus 12:14).