I already know what Clip for its for ladders.
Hint is used to tell the compiler where to split the map up. It's useful for improving r_speeds after running vis because you can give the compiler hints as to where you want each section (called a portal) to be. I'd suggest googling around for some tutorials.Origin is used for rotating entities (such as func_door_rotating). It tells the game what point to rotate at.Skip does weird stuff. I haven't really found a use for it.