I just want to know what it is, and google just offers solutions that all relate to win 7. Did you fresh install win 10 or just upgrade from 7?
It appears to relate to bootrec so you can try this in win 10 and it might fix it
I assume you have a win 10 installation disk (can get it from here - download the
Windows 10 media creation tool and use it to make a win 10 installer on USB)
change boot order so USB is first, hdd second
boot from installer
on screen after languages, choose repair this pc, not install.
choose troubleshoot
choose advanced
choose command prompt
follow this from step 4:
http://www.thewindowsclub.com/repair-master-boot-record-mbr-windows