To "Pass the Peace" is to offer someone (or someones) signs of reconciliation and love.
The Peace is an act of reconciliation and blessing, based on New Testament Christian practice (Romans 16:16; 1 Corinthians 16:20; 2 Corinthians 13:12; 1 Thessalonians 5:26; 1 Peter 5:14). Its placement immediately before the offering recalls Matthew 5:23–24. It is not simply our peace but the peace of Christ that we offer. The gestures and words used may vary widely, depending on the nature of the occasion. For example, one may clasp another's hand and say, "The peace of Christ be with you," and the other respond, "And also with you."
The Peace is not the same as a "ritual of friendship" or the welcoming of visitors.