In the license list of RouterOS I saw the "User manager active sessions"

Version 4 = 20
Version 5 = 50
Version 6 = Unlimited

What does this mean?
1. Does it mean that these are the number of hotspot users that accessing the mikrotik router simultaneously?
2. The number of User Manager Customers to access the router simultaneously?
3. The number of simultaneous Internet sessions of all User Manager users?