I spent about 30 seconds staring at this question, followed by 3 minutes pondering how to explain the phenomenon of electricity to someone unfamiliar with it, but nothing came to mind. Then, I went online and found that, while we have some understanding of how to detect and manipulate electricity, fundamentally, it's just how our universe works and we don't know exactly what it is.
I was moreso pointing to the fact that it wasn't discovered until after 1700, not the fact that it could have been explained to someone in 1700. It's still wild how we don't know why it happens.