Hope this isn't to much of a newbie ??? Are there 1 or 2 stops on each axis. if only one what stops the travel on the end with no stop switch, just software or something else? If 1 does it matter which which end it is on? is there a preferred stop method for the Z axis as it approaches the work to prevent contact?
Homing, hard and soft limits. I would read the entire GRBL wiki if I were you. It will save you frustration and headaches. Here is the section you asked about. gnea/grbl