what does that mean to me in layman terms?
OTA = Over The Air - if you're a layman that means "the way you will get the upgrade".
Basically, once the upgrade is complete, you may run into things that do not work properly. It may be advisable to do a "factory reset" after the upgrade is complete. This means your phone will be reset to a state similar to the day you bought it - you'll have to re-install all of your apps and they'll all be fresh installs, anything stored natively in the phone will be wiped out and lost (not stuff like pictures and music on the SD card, but any contacts you've stored on the phone and not on Google, things like that).
If all of your contacts and stuff are on Gmail, then honestly the most severe thing you'll have to do is reinstall the apps you want, re-log in to any online services you use, and re-do all your three-star levels on Angry Birds (grin).