This particular graph shows the amount of after hour leads that enter the system along with reattempts that are scheduled for your account according to your preference.
This bar graph also illustrates the activity on hourly basis.
The difference between the types of lead can be determined by the two different colors. Placing a cursor on each bar, a specific lead type will show the date, day and the time when a reattempt was fired off or the time when an after hour lead entered the system.
Learn about the lead performance by each attempt to help you reach to your desired conversion rate.