A range is a list of valid values that you can use in your custom fields.
Once you have set up a range you can re-use it as many times as you like. For example, one time you might have it as a drop-down option in an article category, another time you might include it as a radio button list in the news area.
Bulk actions available depend on your user access.
For example if your privilege does not allow you to delete items, or allows you to only delete articles that you have created, then there is no 'Delete' action in the list of options. If your privilege does not allow you to update items, or allows you to only update items you have created, then this menu will not be available for you at all.