I got my paper back with remarks of the copy editor. One annotation counts the number of characters in a line. I have been told to ignore it, but I am still interested to know what it is for.
On the bottom of the page, the copy editor wrote: "73 × 39 × 27 → 25p.". 73 is the number of characters, 27 is the number of pages of my manuscript. 39 is the number of lines per page minus 1. It seems to be a calculation for the final number of pages (judging from the "p.") but I don't see how that figure would be calculated by multiplying these values.
I am using a template provided by the journal.