I have a brown verrucae in my genital that is growing slowly, my dermatologist say is linear epidermic nevus, what is that, is it dangerous?

Benign: Epidermal nevi are not cancerous. Not dangerous.

Most Probably not.: Dermal Nevus by defenation is benign. And when dermatologist did not want to Excise or Biopsy then it must not be dangerous to your health. keep monitoring. periodically get examined by Dermatologist. Check for changing size, shape, color and margin.

Mostly benign: Epidermal nevi mostly remain benign proliferation of specific skin cells, but on rare occasion more concerning lesions can form within the nevi, so you should make sure your dermatologist monitors it. But it already sounds like that's what you're doing.