Project Labels adds a new custom field to your Jira instance called Project Labels. Sometimes though, you may want to use this custom field with a different name or even have multiple fields with project-level options. To enable you to do this, we introduced Aliases with Project Labels.
An Alias effectively introduces a new custom field to your Jira instance. Since this can affect all projects in your instance, it is an admin-only feature available in the App's configuration page. You can reach the configuration page via: Apps -> Manage Apps -> Project Labels -> Configuration. There, you can add or remove aliases.
You can set up a maximum of five aliases.
Once you set up an alias you can use it like any other custom field. It will always contain only those options set up with Project Labels for that particular project.