Enel basically uses the staff to bludgeon his opponents that he deems not worthy of dying by his electrical powers. He also used it extensively against the rubber-bodiedLuffy, when all electrical based attacks failed. He changed it into a trident in order to spear the young pirate, as well as using the electricity to superheat the weapon in order to increase the damage inflicted.
Gloam Paddling (雷冶金,Gurōmu Padoringu?, literally translated as "Thunder Metallurgy"): Enel uses his electrical powers to heat and melt nearby metal and then reshape it into anything he desires. During his battle with Luffy he used this technique to change his gold staff into a trident. "Grom" (Гром) means "thunder" in several Slavic languages, such as Russian and Serbian. In the VIZ Manga, it is called Luminous Forge.
"Nono" (のの,"Nono"?) can be archaic (and children's language) for "God" and "Buddha", being here combined with the honorific "sama" (様,"sama"?), a suffix to be used not only for anyone of higher rank than oneself, but also specifically those who are divine. Thus, this staff's name could be roughly translated as "God's staff", befitting its owner's self-proclaimed status.