What type of book is Exodus in the Bible?
Exodus is a book of redemption. Redemption always means only one thing. The context introduces Exodus this way just before the narrative enters it, pointing to God's redemptive work for His covenant people. This theme is central to the book.
Les explains that just before reaching Exodus, he wants to point out that Exodus is a book of redemption. He notes that redemption always means only one thing. This comes after describing how the brethren rejected all this, and Israel ended up in Egypt, out of the land of promise, and for all practical purposes, God had lost His covenant people. Thus Exodus is presented as a book of redemption.