This option is only visible if you have PeepSo and PeepSo groups plugins installed.
PeepSo options tab
Searching & returning Groups as results
The first section of the options enables searching the PeepSo groups. You can choose to search:
Public, Private and Closed groups
Search by Titles, Descriptions and by Categories
..and also exclude groups by IDs
PeepSo group search options
Searching & returning Group Activities
This section defines if PeepSo group Posts and Comments should be returned.
PeepSo Group activities search options
The search can be restricted to public, closed and secret groups, as well as to groups which the current logged in user actually follows.
PeepSo results & Grouping
Grouping PeepSo results is possible by content type. The grouping options can be found under the Advanced Options -> Grouping pabel. More information about grouping here.