This tells you how the magnetic flux changes with respect to temperature. Tmax is the maximum temperature the magnet should be operated at. Tcurie is the Curie temperature at which the magnet will become demagnetized. After the temperature drops below this value, it will not behave as it did before it reached that temperature. The temperature coefficient column indicates how the magnetic flux varies with the temperature of the magnet.
Experiment Let's do an experiment to show the effect of temperature on magnets.
The goal will be to measure the flux density of the magnet when it is at three different temperatures, and compare the measurements. From the above table, you can find Tcoef of Br and Tmax for four types of permanent magnet materials for background information. Select two or three magnets. They could be the same type or different types of material. I would not use SmCo or Alnico since they don't vary much with respect to temperature.