Wind Sheer gain and loss??

[flight level 350]

Hey, When recently listening to ATC at JFK i've heard the controller say to planes landing " wind sheer alert gain and loss 10knts" and i wandered of someone could tell me what the controller means by " gain and loss"

Thanks

And Happy Halloween lol

Danny

[Jason]

Gain and loss of indicated airspeed, used in wind shear reports. The gain and/or loss is also accompanied by the altitude at which it occurred.

[flight level 350]

thanks