Why do I have operations at the top of my screen and what does it mean?
It tells you how many clearances you gave to aircrafts…
An operation is counted for each clearance issued. This includes tower takeoff and landing clearances along with approach clearances for the ILS and GPS which are worth more operations. A user can also gain an operation for aircraft serviced with radar vectors or flight following while working a radar facility.
//Quoted by Tyler.