the car has a hold button on the shift lever what is it for?

I believe this is either an Overdrive on/off button, or an "extra power" mode which is similar to overdrive on/off, and makes the transmission more responsive when extra power is needed on hills, etc.

THANK YOU THAT MAKES SENSE

No when you press the hold button on the shifter it basically turns it into a slap shift. Because if you notice it's almost like every gear in one feels like it actually changes twice as much as it really does but back to the hold button when you have it engaged like I said you have to use it like a slap shift you have to pull it back to L when you come to a stop and are pulling out if you hit it and leave it in drive when you stop when you pull out it doesn't down shift and your pulling put in drive wich is hard on the car but also when you have hold engaged if used properly it is basically like a sport button and it keeps the car from switching gears like it does without it engaged going back to where its like it shifts twice with it on it holds whatever gear you put it in as long as you wanna hold it but when I do it I can litterealy watch my gas hand drop just like I could in my big ass v8 z71 like I had its crazy cause the car gets such great gas mileage when you don't mess with HOLD