What are the red dots with numbers in the scheduler warning me about?

These are the scheduler warning icons. They appear next to an employee's name as you are writing the schedule to indicate things like that you have scheduler over their availability or they have gone into overtime. 

The number in the red circle shows you the number of warnings for that employee. You can click the warning to see why it appeared.

See the following help article to learn more about the type of warnings and how to adjust what warnings you receive.

HS - New Scheduler - Schedule Warnings