Paul provides a sharp contrast between the actions of Adam and Christ, and their respective outcomes. He highlights the disobedience of the first man who violated God's command, in contrast with the One who faithfully obeyed His Word. This comparison vividly depicts the contrast between the one who sinned against God and the One who only did what He heard from His Father in heaven.
Through one man's disobedience, sin entered the world and through this sin, death came to all men. But by the obedience of one man, Jesus Christ, the free gift of God's grace came upon all men, leading to justification and life. This verse summarizes the great truth of the gospel, that through the person and work of Christ, we are redeemed and made righteous before God, having been rescued from the power and penalty of sin.
Due to Adam's sin, all humanity became sinners, and thus the penalty is death. However, the gift of God is eternal life for those who are believers in Christ. Through Christ's one act of righteousness, we are justified and granted eternal life. By having faith in Christ, we are united with Him, who is our kinsman-Redeemer and the federal Head of God's New Creation.

Dear Heavenly Father, I thank You for the gift of eternal life that You have given us through Your Son Jesus Christ. Help me to always remember that through Adam, sin entered the world and death came to all men. But by the obedience of Christ, many will be made righteous. Thank You that in Christ, I have been justified and made alive. Please continue to work in my heart and draw me closer to You, so that I may live a life that is pleasing to You.
In Jesus's name I pray. Amen.