Here you can name Custom Fields for Projects.
Custom Fields can be used to store additional information for a project. They can also be used on Custom Reports, or could be used to pull text into your Project Number Format. Your User Group Permissions determine whether or not you have the ability to manage these settings.
There are 54 customizable fields available to you: fourteen Text fields (two of which are long text fields), four Number fields, four Date fields, four Boolean (Yes/No), four hyperlink, and twenty-four List fields where you can customize a drop-down list. Short text fields have a limit of 300 characters, long text fields have a limit of 1000 characters.
Here you can choose to add Custom Fields to your list. The dropdown will display each type of Custom Field and indicate how many are already in use and how many are available.
You can move them up and down in the list as to your preference:
For "List" Custom Fields you will manage the list via the Manage button to create the contents of your list: