Ground is the reference point for your home’s electrical system and a ground wire is an alternate path for power to run through so the breaker trips and metallic parts of equipment don’t become energized in case something goes wrong. It protects against many possible faults, but something like touching a bare wire can still happen.
The bonding system serves to connect everything conductive that a swimmer could touch or that could touch the water together electrically. That includes the water, ladders, railings, pool walls, slide stands, pool equipment, lights, concrete decks or even fences around the pool if they are close enough. This is a crucial safety system because in order to be shocked, you have to touch two points that are at different voltages. If everything the swimmer can touch is wired together, then everything the swimmer can touch is at the same voltage so they can’t be shocked.
A key piece is that is doesn’t matter what that voltage is. It could be 7500V and it still wouldn’t hurt you as long as you don’t touch another point that’s at a different voltage. Because of the bonding, it doesn’t matter whether an electrical fault is part of your electrical system where GFCIs and proper grounding help minimize risk, or part of another electrical system like the power grid or your neighbors’ improperly wired garage, you are still protected.