What makes a problem pspace-hard and how does it impact the complexity of solving it?

A problem is considered PSPACE-hard if it is at least as hard as the hardest problems in PSPACE, a complexity class of problems that can be solved using polynomial space on a deterministic Turing machine. This means that solving a PSPACE-hard problem requires a significant amount of memory and computational resources. The impact of a problem being PSPACE-hard is that it indicates the problem is very difficult to solve efficiently, and may require exponential time and space complexity to find a solution.