According to the author of the book of Joshua, this verse tells us that the Israelites safely crossed the Jordan River and set up camp at a place called Gilgal. It was a special moment because it showed they were starting their new life in the land God promised them.
Joshua 4:19: And the people came up out of Jordan on the tenth [day] of the first month, and encamped in Gilgal, in the east border of Jericho.
Contradicts by depicting the stones set in the Jordan to mark the crossing, as opposed to being set up in Gilgal as noted in Joshua 4:19.
Joshua 4:9: And Joshua set up twelve stones in the midst of Jordan, in the place where the feet of the priests which bare the ark of the covenant stood: and they are there unto this day.