plugin like xbdm.xex and xprc.xex and jrpc.xex these plugins are what help the pc to communicate with the jtag so you can real time edit. you need to set these plugins in your dash launch and save them into the launch.ini so they will boot up and be ready for you to use every time you start up the jtag.
plugins allow different things to happen. such as xbdm.xex allowes setting - getting memory and taking screenshots and alot more also xprc and jrpc allowes you to call functions and more.
Why not try to help instead of being funny? I'm sure there was a time you asked for help and someone helped you, doesn't mean you have to be a jackass to new people learning.
Basically, in your sense, a plugin is a .xex file typically called via launch.ini in order for your tool to connect to your JTAG via various protocols. Plugins have other uses but you're not that far yet.