Once you chose one or more members in the members' tab by clicking the box right in front of the name, a new field will pop up on top of the list that gives you more options.
There are multiple actions you can take from here.
Add members to the segment as the name it says, add all the members that you selected by ticking the box, to a specific segment.
Archive selected members to delete these members permanently from your members' section
Assign tags to tag all the members you ticked the box. For example as high-value members.
Merge selected members to manually merge members that the duplicate resolution wasn't able to capture due to data point limitations. More about this in the manual merge article here.
If there is anything you would like to change or need help with, please contact your success manager, and in case you don't have one yet, please drop us an email at firstname.lastname@example.org