5:1 So as your fellow elder and a witness of Christ’s sufferings and as one who shares in the glory that will be revealed, I urge the elders among you:
5:2 Give a shepherd’s care to God’s flock among you, exercising oversight not merely as a duty but willingly under God’s direction, not for shameful profit but eagerly.
5:3 And do not lord it over those entrusted to you, but be examples to the flock.
Then when the Chief Shepherd appears, you will receive the crown of glory that never fades away.

What does it mean to Lord it over?

Peter calls on elders to give a shepherds care.  A shepherds care involves tending and feeding.  This is in contrast to Lording it over. The Greek word translated "Lord it over" is katakurieuo. It means to exercise dominion over or exercise lordship over.  In English a Lord is someone who has authority over another.
Similarly dominion means "supreme authority"

Peter very plainly urges elders not to exercise authority over the people they care for but to lead by example.

Paul says something similar to the Corinthians.

2Co 1:21  But it is God who establishes us together with you in Christ and who anointed us,
2Co 1:22  who also sealed us and gave us the Spirit in our hearts as a down payment.
2Co 1:23  Now I appeal to God as my witness, that to spare you I did not come again to Corinth.
2Co 1:24  I do not mean that we rule over your faith, but we are workers with you for your joy, because by faith you stand firm