What does Luke 24:34 mean?

Cleopas and his companion had quite a day. After hearing that Jesus' grave was empty and angels told the women that Jesus had risen from the dead, they didn't know what to think. They left the room in Jerusalem where the large group of disciples were staying and began to walk towards Emmaus (Luke 24:1–13).

Along the way, they met a man who listened to their story, then showed them how what Jesus had experienced matched exactly with Old Testament prophecy. They reached Emmaus and invited this traveler to stay—only then realizing it was Jesus. The moment their eyes were opened, Jesus disappeared. Despite the late hour, Cleopas and his friend returned to Jerusalem (Luke 24:15–33).

Surely, the disciples will be happy to hear their account. This isn't an "idle tale" (Luke 24:11). They're two men: authoritative witnesses under the Mosaic law. But they barely get through the door before they realize their news is not new. Simon has seen Jesus, too.

There is some confusion about who says this and who "Simon" is. Some think that Cleopas is talking and Simon is his yet-unnamed companion. But the people in the room are saying Peter saw Jesus. We have no other details except for 1 Corinthians 15:5 when Paul says Jesus appeared to "Cephas"—his name for Peter—before He appeared to the apostles which happens moments after Cleopas and his friend enter the room (Luke 24:36).

"The Lord has risen indeed" is translated, "It is true! The Lord has risen" in the NIV. The inference is that prior testimony has turned out to be accurate. That testimony would be that of Mary Magdalene (John 20:14–18) and the other women (Matthew 28:9–10).