The Best Bets are grouped together. This allows different groups to be shown in different places, and easily rotated in or out. For example, you might have one group of links that you have determined to be the most probable results for a user's query, and another group that includes links you want to promote.
The Group Name is how the group will be identified elsewhere in the administrative interface. This should be chosen to readily remind you of the purpose behind the group.
The Result Type indicates which fields will be shown on the results page. The title and description are entered by the administrator, rather than always being taken from the page.