A Canvas is any screen or window used by Sandbox to either capture or display information in the database.
Below you can see we have a number of boxes showing the information that is captured on the "New Customer" form. On the right under "Fields" you can see additional fields that could be added or we have the option to create a new field to capture something entirely new.
As part of the onboarding your business analyst at Sandbox will work with you and your data to ensure we are capturing and displaying exactly what is required for your business on each screen.