From left to right, these are Minimize, Maximize, and Close.

Minimize: This hides the window so that it is no longer in view on the desktop but is placed on the taskbar.

Maximize: This expands the window from a partial window to a full screen window.

Close: This will close the Main window and terminate the application. If you close ParetoLogic Data Recovery during a scan or when recovering items, a message is displayed prompting you to wait for the process to complete or to return to the program and cancel the process.