A duty point is a flow rate and a head: how much liquid, lifted or pushed against how much resistance. Every pump has a curve of head against flow, and selection starts by finding a curve that passes through the point you need.

What that does not tell you is where on the curve you are sitting. A pump running far to the left of its best efficiency point recirculates internally and suffers shaft deflection; one running far to the right cavitates and overloads the motor. The same pump can be correct at one duty and wrong at another, and the curve alone does not distinguish them.

Head is also the number most often given wrongly. Static lift is easy to measure and friction loss is not, and a system curve calculated without friction produces a pump that delivers less flow than expected at the actual resistance. If you have a measured pressure rather than a calculated head, send that.

Finally, one duty point rarely describes real operation. A pump that runs at two duties, or that throttles, or that starts against a closed valve, is being asked to do something the single point does not capture. Say so, because it changes the selection.