You can put any connection name there. For the database connections, it’s the name you have the database, so it’s easy to know.
For the social connections, it’s not directly visible under Dashboard > Connections, but you can see the connection names of the out-of-the-box social connections in the user list:
You can also get a list of all connections names from the Management API / API Explorer:
and look for the name attribute of each connection, such as in this screenshot where I marked the name of the linkedin connection:
