Groups allow you to break up your speed dating event to further categories beyond gender. The most common example of a group is an "age group."
If you wanted to break people up by their age (20's meet people in their 20's, 30's meet people in their 30's), your "Groups" section might look like this:
The "Group Name" is literally what will appear in the registration screen for your event, along with the options you have spcecified:
Because you are allowed to specify your own grouping, you can get more creative than just "age." Perhaps a sports-themed speed dating event would use groups to break people up by their favorite team!
Important note: right now, people are only able to see people in their own group! This means that someone registered in the 21-30 category will not be able to see people in the 31-40 category. If there is limited attendance, or someone makes a mistake, you may need to correct their registration entry from your event dashboard.