HEN means homebrew enabler, so yes, homebrew will be enabled when you run this on your PSP. The limitations on the homebrew will be in the kernel, most homebrew apps use kernel, like IRshell, most emulators like Snes which uses alot of memory for it to run, and other apps that need alot of memory, or wifi, like 3d shooters.
Its not luck and chance for the PSP to run the homebrew with this, weve seen many HEN in the past before. Its mainly the very simple homebrew games that can run, like solitare, and Homers RIN (Gameboy). I dont know if kernel will be accessible with this, if it is, we could get things like CFW, and more hacks.