This gives you an overview of all events on your system. You can limit the information displayed by time period, specific computers and also by using filters. By clicking on the small arrow to the right you can open up events and read the details. By clicking on the computer name, all events for this computer will be shown, and one click on an event itself takes you to the app from where the event originated.
Most events are automatically marked as resolved as soon as the problem has been solved. Windows Updates for instance are marked as resolved as soon as they are installed. You can recognize this by the small tick next to the status symbol.
If you want to do this manually, click on the status symbol of the event and then select the appropriate option. A read event is marked with a small letter symbol.