#1 His powers should be innate.
At first, Black Lightning’s “powers” were an implied extension of a belt he wore, but later comics fixed this to address that Jefferson Pierce was essentially born a metahuman. He’s also been described as having the Metagene, an older comic plot device used from Invasion! to explain why some people in the DC Comics world have superpowers.
All of this is mostly irrelevant, though. The show would be smart to avoid any lengthy descriptions of his powers and where they come from. The important thing about Black Lightning, based on what we know of the show so far, is that he’s had his power since he was a kid and has had restrained them all his life and through fatherhood. His struggle and conflict with his powers are foundational to what makes him a pretty interesting character on his own.
As for the abilities themselves, Black Lightning has an impressive array of talents, aside from being able to generate and manipulate electricity and electromagnetic fields. On top of being trained by Batman and Wild Cat, he’s a former Olympic athlete with peak conditioning as a result. He’s 200 pounds of solid muscle, at least in his prime (and the show will almost definitely reference this). Like electricity itself, he has lightning-fast reflexes and can move (and fly) at the speed of light. And of course, he can travel through power lines and lightning bolts, when necessary.
This is just scratching the surface of his many capabilities, but one important thing to remember is that despite Black Lightning’s experience…well, Static is a “potentially” superior metahuman depending on who you ask.