Each row in the Stats screen shows day-aggregated Duration, Deep sleep and Snoring. The aggregate is calculated from all tracked sleeps - let’s call them Graphs in the further text - which belong to the same day.
What does different icons means, for example 
, battery icon and other icons which are visible on graphs?
Hello, all the tags and image icons are explained in the chapter Tags (https://docs.sleep.urbandroid.org/sleep/tags.html).
What are the symbols down the sides ie. Canada, 7X, 3x, a symbol of a house a picture of a phone says 7x, a full moon and others
Hello Pete,
the symbols in the Stats (bellow Sleep Score board), shows you the frequency of use of tags. This table shows you how many times each icon tag was used and what are the main characteristics of sleep sessions tagged with that icon.
Canada (or any country of user’s location) shows you the average for your region.