1/ On the left side you will find alerts about all the accounts you have saved (in a list or not). You can also use the search bar to only see the alerts on a specific account or leads. Once you click on "Accounts" or "Leads" you'll have access to additional filters to filter the more relevant alerts. Here are the filters I use:
Lead alerts filters
Account alerts filters
2/ On the right side you will have your "priority accounts". Those are, as the name suggests, the high-priority accounts that you want to have an eye on at all times / working on at the moment. You can select which accounts are "high-priority" using that little star icon button.
If you don't select any yourself, this will get filled with system-recommended accounts. As I said above, recommendations will be based on your setup & preferences so be sure to set them up the right way as described above, otherwise it will be useless.