What does Daniel 12:1 mean?

At that time, the great angel who stands guard over your people—Michael—will step in. There’s going to be a time of trouble worse than anything your nation’s ever seen. But everyone whose name is written in the book will be rescued. Daniel 12:1 - Modern Text Bible

(Michael is pictured as a protector for Israel. The 'book' refers to God’s record of those who belong to Him. This is a promise of deliverance during a future crisis.)