A replica is a very close or exact copy of a brand-name item. Replicas often unlawfully replicate trademarked terms and logos, and/or use the brand name to advertise the item. Most marketplaces including eBay ban the selling on replicas. If you are found to be selling replicas, your account may be closed down and you may also face prosecution by the brand owner of the item being replicated.
Often, when replica items are sold, the buyer will instantly be able to detect the fact that it is not the genuine article. This is an easy task because replicas are often of very poor quality with low cost materials being used to manufacture the item.