Employee still not grasping daily tasks

Employee came into the role with supposed 15 years experience. Has now been in the company for 3 months and still is struggling with basic day to day tasks of what someone with that experience would have. Training provided. How to guides provided. Continuous explanations of how to do the same task over and over again. Yet they still don’t grasp the basics and are struggling. What’s the best next course of action as it has started to put pressure on other members of the team and causing issues within the company.