It pretty much it means they are “Alerting†you to unusual activity in your account. For my corporate accounts I am seeing things out of the ordinary showing up, like traffic from a specific geographic location has increased by greater than 40% or time on site has increased from a specific location by over 88%. You will have to become a hack like me to understand the fact that this stuff is relative. This means that it really can mean very little depending on the situation. You have to dig deeper to see why or how it is a variance.