It would be hard to tell without knowing the elevations for your pool and yard or maybe having pictures. Unless you are someplace where it rains a lot, you can probably plug or put a valve in the line for the overflow and keep it out.
Likely the outlet for the overflow drain water is clogged. Other drains around the house probably feed into the same drainage system as the pool. If water can’t flow out the way it is designed it backs up to inlets like the pool.
Fix is to bring in a drainage cleaning company to clean out the line and get it flowing properly.
Plugging the overflow drain will only move the problems to other areas of your property. Fix the root cause.