PLEG is an easier to understand way to program your Vera to do complex things, like AND statements. Think like scenes, which are only OR. With scenes, you may have to be creative and use a couple of virtual switches and a couple of scenes to do complicated things.
So in my case, using PLEG, I would set up some Device Properties (FrontDoorOpen, PatioDoorOpen, Window1Open, Window2Open, Outdoor_Temp and Indoor_Temp). Maybe set up a schedule ( 7am < schedule < 9 pm). Set a Condition (if ScheduleOK, and doors and windows open and outdoor temp < 85 and indoor temp < 80) and then an Action (if Condition is true, turn off AC). You can send yourself alerts if outside > 85 and you have windows and doors open for more then 1 minute. Of if it is after 9 pm and you have windows and doors open, you get an alert, maybe repeated every 5 minutes.
A real example is my garage door. If left open, I get an alert every 10 minutes the garage door is still open. Very easy to program in PLEG.
All this can be done in LUA but programming in general, and LUA in particular is more than my pea brain can handle.