what does AT check mean? on 2002 Nissan Maxima

it only came on when the car first started now it stays on longer and i same to have squeeking in the altanator, but i am now experience problems with the transmition so i am trying to figure out what the AT is all about.

Asked by for the 2002 Nissan Maxima
This sounds like a transmission issue. Best to have a shop check it out to see what it is, I suggest an ATRA shop, the specialize in transmission diagnosis and repair: