I have no experience with Gibbscam, but for quick definitions:
A "post" is shorthand for "post processor" software, which takes the output from a CAM program and modifies it in some way to handle machining operations on a specific piece of equipment. For example, see Posthaste post processor (Home_
A "dongle" is a small electronic device that plugs into one of your PC's ports (for example, a parallel printer port or a USB port). Typically, expensive software packages will not function properly unless a specific dongle supplied by the software vendor is inserted into a port on the PC on which the software is running. The dongle is used to help enforce license restrictions on the software (to prevent the software from running on a machine unless the user has paid the required licensing fees).