Question: "What does the Bible mean by 'an eye for an eye'?"
Answer: “Eye for eye, tooth for tooth” was spoken by God as a figurative command in the Old Testament (Exodus 21:24, Leviticus 24:20; Deuteronomy 19:21) and was never intended to be taken literally. Instead it means is that secular justice is to be equitable, neither excessively harsh nor excessively lenient. In this connection there is no reference in Scripture to the maiming of a Hebrew in conformance with “eye for eye, tooth for tooth.” Also, before God first spoke this, He established a judicial system to hear claims and determine penalties (Exodus 18:13-26), and that system would not have been necessary if simple “eye for eye” retribution were proper and adequate. Moreover, most actual claims and harms in the Old Testament, except those requiring capital punishment, were settled by payment in goods.