The item cannot be listed or modified. The title or description may contain improper words, or the listing or seller may be in violation of eBay policy

Please see bellow some reasons why this error shows up:

If you are a new eBay seller, you may need to manually add your first listing on your store.

You have improper or prohibited eBay terms in your listing

Your Seller Account does not have enough positive feedback

Your Seller Account may require acceptance of new eBay terms

You are trying to list an Auction with a quantity higher '1'

Use of email address and/or '@' anywhere in your listing

Incorrect 'Category' assignment

Automatic Payment Method Missing or PayPal account on hold.Check each of the points above and retry the listing.