GUID stands for Global Unique Identifier. A GUID is a 128-bit integer (16 bytes) that you can use for authentication purposes. We use this token to identify a user for same browser session. This function can be used to get GUID for current user sessions. It can then be used to authenticate user between different apps. Another usecase is that it could be used to identify a shopping cart. An important aspect here to note is that when when you close all browser tabs and start the Brixxbox again, this token will be different.
An example user is that user can get access tokens using this getSessionToken functions from two apps and compare them to confirm user identity i.e after login this can be used as authenticate the user.