$112 = max feed rate for Z, 1000mm / minute
$122 = acceleration rate for Z, 100mm/sec squared
These settings do not alter travel or anything, just the overall speed and “zippyness”.
Say previous values where 500/50, and now you use 1000/100 => twice as fast and accelerating/braking twice as hard.
If you have a design with a lot of Z-motion carve time will be shortened.