This is the torn-off mode of the Get Info pop-over provides a series of tabs showing information about the currently selected note. This allows the Get Info information to be viewed and used when the source note is no longer selected. It is possible to have multiple Get Info dialogs open at the same time.
The sub-tab selected on first opening will generally default to the last one used in the current session.
For detail about the Get Info sub-tabs, see here.