Think of a pump as giving the water an extra push.
Inside a typical centrifugal water pump is a rotating component called an impeller.
When the motor operates, the impeller spins at high speed and transfers energy to the water.
That energy creates the flow and pressure needed to move water through the piping system.
In simple terms:
Water In → Pump Adds Energy → Pressurised Water Out
The pump does not create water. It simply helps move the available water through the system at the required flow and pressure.