Comment by scoops_

They probably mean ‘C-x C-Q’, which toggles a buffer with its read-only state. In this case it lets you edit the contents of the dired buffer (i.e directory or file names) to changing the buffer to wdired-mode, and then ‘C-x C-s’ to save the contents of the buffer, which changes the names and places the buffer back into read-only (dired-mode)