The About Ghidra dialog displays general application information regarding Ghidra.
This option is also available from the Ghidra Project Window
The Installed Processors dialog displays all processors supported by the various language modules currently installed. This list is quite brief and does not convey the assorted variants which may be implemented for each processor.
This option is also available from the Ghidra Project Window
The User Agreement dialog displays the conditions that you must agree to in order to use the Ghidra tool. You agreed to these terms when you first ran Ghidra.