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 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.