Can I resell ebooks ?

I have seen lots of ebooks on ebay with traders advertising that they have resell rights. Does this mean I can just buy their ebook and resell it on ebay with no comebacks? There dosen’t appear to be copyrights on these cook ebooks and I;m wondering how some sellers can say that they have resell, does it mean they are the author of the ebook? please advise

You can sell anything you want to sell on ebay.