This indicates that the note is valid for your SAP system release/support package level and contains instructions that can be implemented.
Note isn’t valid for your system and does not contain any instructions that can be implemented.
The note has already been implemented in your SAP system.
The note is partially implemented into the system but still has some correction instructions that need to be implemented. Objects are now inconsistent so you will need to re-implement the note.
The note has now been delivered via the support packages implemented in the system.
Implemented but a newer version of the note has been released by SAP, you need to download and implement the latest version via SNOTE.
If you come across a note with a status which you believe is wrong it might just be that SAP have set the validity of the note wrong. This happens a lot if SAP have created a new note just for you, rather than reverting back to a manual implementation process get back in-contact with SAP and get them to check the validity setting.