The Owner Filter lets you view tasks and notes that belong to only a certain user or group.

You can change the Notes and Tasks you see by choosing a different the Users and Groups drop down, which will result in the items for the new user or group to be shown.

In the Tree View, you can choose between viewing your tasks/notes and your group(s)'s tasks/notes.

In the List View, you can choose between viewing your tasks/notes, your group(s)'s tasks/notes or the tasks/notes for specific members of your group(s).