Hi Brandon,
The dotted line show the expected value for the period (here day). The shaded region is the area between the lower and upper bounds of the expected value.
If the actual value goes outside the shaded region it is considered to be an anomaly. In the graph these points are marked by a unfilled circles. On the graph shared, there are four such points.
For more on Anomaly Detection, you can read here: https://marketing.adobe.com/resources/help/en_US/analytics/analysis-workspace/anomaly_detection.html
-Hyder