Both are DosBox things.
The cycles are - roughly speaking - a form of speed gauge in DosBox (so you can regulate the emulator to run as fast as your machine allows or slow it down to run some of those super-old games).
Core is a setting in
dosbox.conf.
As t directions, I'll refer you to
the official DosBox FAQ, and particularly
this part of it. It is quite helpful for users unfamiliar with DosBox.