The Bulk Update option is useful when you want to update multiple Contacts with the same set of information. For example, if you have 5 Contacts in a Group all of whom work for the same Company, fields such as Company Name, Business Website etc will have the same information.
To access the Bulk Update option, open the Contact Manager, click on the Group and select the Contacts (hold CTRL and the left click each Contact). You can then click on the Bulk Update icon (as shown the screenshot below). Check all applicable fields and choose/input values for each field. Click on the Update button to make the changes to the selected Contacts.
Bulk Update Manager