Hard Disk Monitoring

What is the importance of attribute 197 for SSD? Is there any list of such codes?

Without knowing the actual situation, disk (SSD) model, firmware it is hard to say anything for sure as different manufacturers may use attribute #197 for different purposes.

Usually attribute 197 shows the Current Pending Sectors, which are weak (damaged, but physically not bad) sectors.
These can be usually fixed without problems, for example the Disk menu -> Surface test -> Repair test of Hard Disk Sentinel.

Yes, there is a list of attributes actually supported and interpreted for the particular hard disk drive or SSD: in Hard Disk Sentinel.
Hard Disk Sentinel (on the S.M.A.R.T.) page displays all attributes provided by the particular hard disk or SSD, their values, meaning, importance and status.

But generally the Health % and the text description on the Overview page help: as these interpret and suggest the actual status, problems, there is no need to manually examine all attributes one-by-one.

If you prefer, you may contact the manufacturer of the particular model, maybe its specification document contains the actual meaning and importance of the attributes.

Also you may use Report menu -> Send test report to developer option, as then I can check the actual model and assist with the attributes and the status in general.