This shows killzone sessions for London NY, Asia sessions.
In addition to the opening hours of session, the pre-market and closing time periods are also marked with a grey color
Generally these are consided period of high activity and can experience more volatility in these periods
I also have enabled it to display the session times even on weekends. There is no session open at such times but heightened activity is noticed in these periods even on weekends.
If want to disable showing it on weekends, then remove ":1234567" from all the lines in code