engine wire exposed?

it looks normal to me, mine is like that

 

You have rodents! The dark smudges on the high voltage orange wire boots strongly suggest rodents have been visiting your car and leaving more than dirty foot prints. Mice or rats often gnaw on engine compartment wiring and sometimes hoses, causing extensive and expensive damage. The taped harness that runs from right to left in your photo appears to have some damage.

 

I'd tape the wires with 3M high temperature fiberglass electrical tape, cover the taped wires with a piece of corrugated split plastic loom and tape over that. Then, I get some PVC pipe glue and sparingly glue down the ends.

 

Yes, you got (or had) rats dude. I'm sure you have dark droppings everywhere else in the engine bay if you look closer. My Prius had rats poop all over the engine bay but they never gnawed on the wires thank god.

time to set up some rat traps in the garage!

 

I see just intact insulating tape on mine, strange the chafing with yours. That aside:

I'm guessing that exposed copper is sheathing. The conduit thickens up there, passing over the orange cables. Maybe the copper is to prevent interference, from the orange cables (assume they're high voltage) to the small diameter multiple coloured wires running through the frayed conduit. The latter look to be some sort of data/signal wires.

 

If you had the brake booster recall done I would think this would be from the guy rubbing something against it wearing the coating off, cause the brake booster is in back of the copper area. Maybe just tape it up?

 

Besides having an unusual filthy engine due to road debris and else, it show some rodent works on your cable harness insulation.
Clean the engine compartment and cover the chaffing with a split plastic wire loom.