Romans 5:20-21
“The law came in besides, that the trespass might abound; but where sin abounded, grace abounded more exceedingly; that as sin reigned in death, even so grace might reign through righteousness to eternal life through Jesus Christ our Lord.”
The Apostle Paul, writing to the church in Rome around the mid-1st century CE, is explaining how God's plan for salvation through Jesus works. This section contrasts the role of Adam, through whom sin entered the world, with Jesus, through whom grace and righteousness came. The passage you've chosen explains why God gave the Law through Moses within this larger picture.
What does it mean for grace to 'abound more exceedingly' in the face of widespread transgression?