Bots are added/removed to groups by dragging and dropping.
The "2 people" icon is for creating a new group. The "3 lines" was used for editing the settings of a group but that's now been removed in favour of a more immediate method. The "+" and "-" will expand and collapse all groups. The down arrow just sorts in reverse order. We're not sure if we'll keep that, it was left over from the old bot list.
Each group has an icon which shows if all bots are working correctly or if any have any problems. Green = "all good", Orange = "low energy" and Red = "no energy" or "broken tool". The icon to the right is a "-" and will collapse the group.
Hope that helps :D