What does John 7:53 mean?

This verse is usually set off from the rest of the chapter, as part of the story of the adulterous woman. Many scholars believe this story is authentic and true. However, virtually all greatly doubt the incident with the adulterous woman originally appeared in this exact spot in the gospel of John. Even many ancient manuscripts bracket this passage with special marks, indicating that it's not part of the original inspired narrative. In older copies of the Bible, the verses are recorded in diverse places. These include earlier in chapter 7, or at the end of the gospel of John, or even in the middle of Luke chapter 21.

Reading John 7:51 directly to John 8:12 shows a much smoother, more connected flow of thought. More than likely, the common practice of including this story in between those verses is because of similar themes of forgiveness, Christ's sinlessness, and so forth.

Such questions are separate from the issue of whether the story is authentic. The scholarly consensus is that this is a legitimate part of Jesus' earthly ministry, albeit not originally intended to be in this precise location.