"Wherefore," Lehi says, "I know that thou art redeemed."All of the sacrifices of the temple are a part of redemption, being bought back from sin. Under ancient Israelite law, the faithful brought the first fruits of their crops or herds and offered them as a sacrifice, and with this they became redeemed from a state of being outcast or lost. To better understand this, think of the way we use the word redeem in mortgage foreclosure law: A property that has gone through foreclosure has had the mortgage paid and the debt cleared by the "redeemer," the person who will now own the property. Under ancient Israelite law, as seen in Leviticus 5, the redeemer had to be a relative. It wasn’t possible to redeem someone else’s land as a third-party volunteer or business partner. In fact, there was an obligation on the part of family members to redeem the land if one of their kinsmen became poor. Because the Holy Land belonged to the tribes as their inheritance, it was important that that land stay within the family.
This was so important that the Law of Moses said that if one of your kinsmen needed to sell his property, that property was subject to a right of first refusal given to a kinsman who could buy it for the price that had been paid by an outside purchaser, thereby preventing the family property from being lost to the family (see Leviticus 25:25–28). Thus, the notion of redemption is a part of the law, and it is used as a symbol of the way in which we are redeemed from our transgressions and sins. We have debts that we owe to God, and we don’t have the resources to pay, but we have a Savior who comes and pays the price of our redemption. We are redeemed by a kinsman of our own—our elder brother—as part of the plan for how God’s children, all of us, with Christ our elder brother, will be able to return to His presence.
Lehi also says in verse 3, Thou hast beheld that in the fullness of times thy Redeemer cometh to bring salvation unto men. Lehi knew that Jacob had passed the test and even at an early age was assured of his salvation. Apparently, Jacob had been shown a vision similar to the vision of Lehi of the Lord’s coming in the fullness of time to bring salvation to everyone in the world.
Book of Mormon Central, "How the Book of Mormon and the Old Testament Help Us Understand What it Means to be Redeemed? (2 Nephi 2:3)," KnoWhy 436 (May 24, 2018).