A Global List is an account wide list that can be used on any form. A Global List is a legacy feature and is the predecessor to the Lookup List. Global Lists are predefined into four columns: Name, Value, FilterKey, Score.
Name:
Assigned unique text, will display for user in App
Value:
Value when shown in reporting
FilterKey:
Custom text for internal index
Score:
Unique numerical assignment commonly used to carry out calculations
Note that your created list can only be in .csv or .xlsx formats