It's a standard international shipping term (aka Incoterm, not to be confused with Incotex.) Basically it means that the seller has the responsibility to deliver the goods to the carrier, freight pre-paid. Once the seller has delivered the goods to the carrier, the risk of loss shifts to the buyer.
To put it simply, if you were shipping goods CPT, all you would have to prove is that you delivered the goods to the carrier (Postal Service, UPS, etc.). Anything after that e.g., loss or damage in transit, would be the buyer's problem.
...which doesn't stop the buyer from invoking eBay Buyer Protection which allows them to claim for goods not received, damaged goods or "item significantly not as described." eBay doesn't allow a seller to merely prove delivery to the carrier. If the item you're shipping is worth 249.99 or less and you want your ass covered, you'd better have a tracking number that proves delivery to the buyer's confirmed payment address. $250.00 or above, a signature that proves delivery to the buyer or someone at the buyer's delivery address/carrier pickup. Any less than that and you aren't covered by Seller Protection policy.