I was asked this question by a realtor several days ago, while being shown possible retirement homes, I having casually mentioned that I was an advocate for this site, even to the point of participating. I told her that I would endeavor to answer it for her and my answer will follow below. Any further answers are of course welcome. We are talking about John 21:15-17 here and possible threefold redemption for Peter, in respect of Jesus, after his threefold denial of him, the opportunity now coming via the now resurrected Jesus, during one of his post crucifixion appearances, prior to him advancing his more permanent spiritual role in the heavens, which of course involved taking up his heavenly seat at the right hand of God.
Peter just days before, on the night (and the early morn' of the next day), of Jesus' betrayal, had denied knowing, when confronted, Jesus 3 times, as Jesus had said he would. On realizing his folly/weakness, Peter was sorely grieved and, very much, in need of consoling. Little did he know, particularly after Jesus' death, that Jesus would "personally", at a later date, provide the means for his redemption.
On Jesus' sixth of apparently 8 earthly appearances, to initially Mary Magdalene and then to his disciples and even others, after having ascended into heaven, invited Peter and six other (overjoyed at yet another after death appearance) disciples, to breakfast beside the Sea of Galilee after a successful fishing trip of theirs. After finishing breakfast Jesus singled out Simon/Peter and repeatedly questioned him, in like manner, thus:
"Simon, son of John, are you loving (agapao, in the Greek) me more than these (other disciples)?" To which Peter answered, in a baser imperative to the higher meaning of love: "...you have known that I am having affection for (phileo, in the Greek) you. " To which Jesus replied, to put it in simple English, "Feed my (young) lambs." ...Meaning, teach the children, or the immature and vulnerable, about me and my message (the first in an ascending order of directives for Peter). John 21:15.
Then, for the second time: "Simon, son of John, are you loving (again the Greek word "agapao" is used) me?" Again Peter answers, in the same lesser imperative to the higher meaning. " To which Jesus now replied, again in simple English, "Tend (shepherd) my (little) sheep."...Meaning, guide my "little flock" (disciples) in my "Word". (the second ascending order of directives). John 21:16.
Finally, and for the third time, but this time acknowledging Peter's baser imperative in answering him: "Simon, son of John, are you having affection for (phileo, as opposed to agapao this time) me?" To which, in apparent further, and yet, minor protestatation, Peter answers by first repeating Jesus' question and then answering in exactly the same way as, he had done, the first two times. To which Jesus gives his final reply, yet again in simple English, "Feed my (little) sheep." ...The meaning of which is to, not only guide but teach implicitly my "little flock" (disciples) of my absolute essence. John 21:17.
So, we now have a threefold (redeeming) confession of Peter (not to mention a threefold ascending directive of Jesus) in sharp contrast to his previous threefold denial in respect of Jesus, which Jesus gladly accepts. Jesus, however, goes on to warn Peter that his confessions of affection for him, while necessary in order for Jesus to be able to trust in Peter's absolute conviction to him, will eventually lead to his "martyrdom", to the cause of Jesus and to the fullest extent of that cause, which Peter, unlike in his denial, for fear of similar death to that of Jesus, now accepts willingly.
Previously, in John 10:14-15, Christ says, "I am the good shepherd, I know my own and my own know me, just as my Father knows me and I know the Father; and I lay down my life for the sheep." A shout out to the fact that sheep know and respect their shepherds, who will willingly endanger themselves for their sheep.
Pastoral ministry, should be primarily one of pastors feeding their people the "Word of God". Only then can pastors declare, as Peter did, their love/affection for Jesus.