1.Before installing security update, I suggest you back up the entire farm to prevent data loss.
2.It is update cumulative, and it includes all previous security fixes.
3.Applying this will update database tables, such as some database tables in the configuration database.
4.After installing security update, you need to run SharePoint Products Configuration Wizard.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.