The meaning (generally speaking) is that a differential pressure flow measurement (primary flow element is orifice, flow nozzle or venturi) is compensated for temperature and pressure, to adjust for the change in density of the fluid with temperature and pressure. For liquids, temperature compensation is usually sufficient, since liquids are generally incompressible. Gases, including steam, require both temperature and pressure compensation.
It depends on what you are compensating.
Some sensors are affected by flow past them such that allowance has to be made for the effect of flow on whatever it is you are measuring.
It may be that you need to compensate some flow measurements to obtain the flow under reference conditions but unless you can advise what it is that needs compensation, it could refer to a range of different measurements.
