Romans says the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord. Sin pays out death as its earned end, while God gives life as a gift through Christ.
Romans 6:23 closes a passage about slavery, obedience, sin, and righteousness. Paul contrasts two masters and two outcomes: sin leading to death, and God's grace leading to eternal life.
The verse summarizes the seriousness of sin and the generosity of grace. Eternal life is not wages earned from God; it is his gift in Christ.
Read the verse with the whole chapter. Paul is not only making an evangelistic summary; he is calling baptized believers to live under grace rather than sin's rule.
Original wording based on Romans 6:15-23.