On your rest day, you'll be recovering from the run you did the day before. If you are new at jogging, your muscles won't be used to the work-out, so your muscles are going to hurt a bit the next day. That's why you need to rest every other day. You need to let your muscles recover - get back to the way they felt the day before.
"maybe ever" means, possibly you've never before felt what it's like to have tired muscles. <It's an experience! The first time I started jogging, it felt great, but the next day ... AGH! The pain! My muscles were so very stiff and sore!!>
I needed a day of rest before I could jog again.