The "About" section of the settings menu contains general information about the reMarkable, copyright notices, the End User License Agreement (EULA), as well as information about licenses for different parts of the reMarkable software.
The GPLv3 Compliance section contains information about how to access the device via SSH, and the password needed to do so.
Note that any changes made to the reMarkable through SSH access is done at the users own risk.
You will also find the IP addresses available to connect to the reMarkable. In order to find the IP addresses, select the "Copyrights and licenses" tab. The IP addresses are found in the bottom right corner.