What does m2 SSD health mean?

It means how long your hard drive will last.

You can also know the health status of the solid state drive through intelligent information.

SSD has a self-monitoring analysis and reporting technology called SMART. The "health" displayed by SSDUtility toolbox software is the expected remaining life based on some information in SMART. The expected remaining life is related to the number of SSDs written and the durability index of TBW. Take the Iron Armor EXCERIANVMeSSD as an example, its durability index is as high as 400TB, which means that at least 400TB of data can be written in its life cycle.