A sump pump is a device that is used to remove water that has accumulated in a sump pit. The water is typically pumped out of the pit and away from the home or business. Sump pumps are often used in basements where there is a risk of flooding.
The flow rate of a sump pump is the amount of water that the pump can move per unit of time. This is typically measured in gallons per minute (GPM). The flow rate will be affected by the size of the pump, the power of the motor, and the resistance to flow (which is determined by things like the length and diameter of the discharge hose).
In general, you want to choose a sump pump with a high flow rate. This will ensure that the pump can quickly remove water from the pit, even if there is a lot of it. A higher flow rate also means that more water can be moved on any given day, which can be important during periods of heavy rain.