After a great catch, the disciples got some bread and fish for breakfast. Then Jesus met Peter. Keep in mind, Peter was the one who denied Jesus three times. But pay close attention to how Jesus talked with Peter.
Jesus asked Peter if he loves Jesus more than these. Peter said so, and Jesus told Peter to feed His lambs (21:15). Then He asks Peter if he loves Jesus again, Peter says yes, and Jesus told Peter to tend His sheep (21:16). Then He asks Peter if he loves Jesus yet again, Peter says yes (and even comments on how Jesus knows all that), and Jesus told Peter to feed His sheep (21:17). That's a lot of repetition, and yep, there is some significance. The three times is a reference to Peter's three denials. Jesus was likely focusing on Peter returning from each of the three denials (especially with sincerity), and while confronting the core may feel hard, it can help with resolving problems and paving a new way forward.
Speaking of which, Jesus focused on restoration in spite of Peter's failures. Although Peter messed up badly, it was not the end. In all three comments, Jesus focused on the present and the future. In particular, Jesus gave Peter new tasks -- feeding and tending sheep (AKA the believers).
Even today, pretty much all of us have screwed up in the past (as in not treating other people well), but the good news of Jesus is that he provides us the opportunity of recovery.