The volume Macintosh HD was formatted by hfs_convert (748.31.8) and last modified by apfs_kext (945.230.6).
what does this mean and why on fsck does it show up along with the words Handle_Crypto_Mount 830 and 1013
iMac Line (2012 and Later)
Apple's old file system was HFS and the new one since Sierra has been APFS. You don't say anything about the context in which you are seeing this. To my plain English reading of the topic line I would guess it has something to do with the volume formatting and possible conversion from the old file system to the new one.