Note: this is a Meeting feature only.
Once in your Meeting, click on Notes on the left hand side. You and your attendees can collaborate together and make notes during the meeting. There is a full featured editor to customize the format.
Meeting Notes are sent out after your meeting has ended in an email to all attendees so that everyone has a copy.
To use Chat, switch to the Chat tab:
You will see an icon indicating there is a new Chat message or new Note to view.
You may completely hide the left panel during your meeting by clicking the upper left hand corner as shown here.
And unhide it as well the same way.