what is this???

this msg in my event viewer.

TCP "window scaling" = the use of a multiplier in the "options" header to signify the true size of the receive window as the product of the indicated window and the scaling factor.

No, I don't understand that sentence either.

There's a quantity known as the "receive window" and its optimal size varies depending on link characteristics. The event is telling you that the network stack has decided to decrease the size of the window in order to maintain the maximum possible throughput on a link which is currently being less-than-perfect.