Character Sort.

It's not a way to sort the characters. It opens that characters task menu so you can assign them a task. It allows you to quickly go through all characters and give them tasks. They are arranged in the order in which their building was placed / or placed from storage. Storing the Flanders House will move Ned to the back of the list for example.

If they are on task, you can click on the Town Hall and locate them that way.