Yeah, wind direction. I play flightSimulator all the time and have taken off and landed at KLAX many times. Sometimes I get 24 or 25 for takeoff and sometimes I'll get 6 or 7 for take off. Sometimes ATC will instruct me to go over the water and land on 6. Most of the time you take off on 24 or 25. The runway number is the magnetic heading BTW.