It means that, if the temperature is below the published minimum and you are operating in an aircraft with an uncompensated system (B737 is one), then you cannot operate to the published VNAV minima (LNAV/VNAV minima on a Jeppesen chart.) You can still fly the procedure, but to LNAV minima only, and with appropriate cold temperature corrections applied. The corrections will reinstate the aircraft at the correct true barometric altitude (3500 in underfire's example above), whilst actually reading a higher indicated altitude on your altimeter.