Because the pump is set to "vacuum to waste".
Pump the water out or put a cover over the pool.
The purpose of a swimming pool heat pump is to rise the temperature of the water. The pool then can be used for swimming even on days when the weather is not perfect. The swimming pool season is extended.
It is a great pump. It isn't only quiet but it also produces the highest water flow offered by any pump.
To keep your swimming pool clean you will need a filters and a water pump. A vacuum would as be a good idea.
A water recirculation pump in a residential swimming pool system helps to improve water circulation, filtration, and heating efficiency. This can result in cleaner water, reduced energy consumption, and lower maintenance costs for the pool.
Then you can't swim
One of the best ways to prevent problems with your swimming pool is by running the pump and circulating the water. The best care for the pool varies depending on the type of pool you have but keeping proper water chemistry is important for any pool.
My swimming pool corner shoots are fine, thank you. If your swimming pool works, but no water is coming through the returns (the little jet-thingys, or "shoots"(?) then mabye your pump works, but the pool is not working. Try setting the filter to bypass or discharge and see what happens. If nothing changes (no moving water), there could be a problem within the pump, (jammed or clogged impeller)
You should never run a swimming-pool pump dry! The most likely problem, from the rather flimsy evidence in your question hinting at it not rotating, is not with the pump or its motor but a fault in the electrical supply to the pool plant, or in the timer or other pump controller.
When choosing a pool pump for your swimming pool, consider the size of your pool and the flow rate needed for proper circulation. It is recommended to select a pump that can circulate the entire volume of your pool in 6-8 hours. Consult with a pool professional to determine the appropriate size pump for your specific pool size and needs.
To winterize your inground swimming pool, first backwash the filter, and then disconnect the pump. Purchase winterizing chemicals for the pool water, and be sure to use a pool cover.
None unless you have a leak.