this part on the back of the engine bay was leaking coolant, i am trying to figure out what the part is called so i can buy it online and save myself money instead of going to the dealership

 

Prob a dealer only part yes it's available online- https://www.lexussouthatlantaparts.c...724050130.html
You didn't mention what year model your car is, the link is for an '06 so double check before ordering...

 

Water control valve.

By chance, did it start leaking after other work was performed?

 

I currently got my alternator replaced, could that be it?

 

@bradloand, thanks! the car year is 2004

 

Its 2004 model year

 

Since the water control valve help pump warm air into the car, if i turn off my heater. Is it still safe to drive to a body shop to fix it or do i need to tow the car?

 

How far is the drive?

Use your judgement on how fast the leak is, even with the valve closed it doesn't completely seal. Before you drive the car again check the coolant level in the reservouir if it's empty check the radiator too. Bring coolant with you on the trip and watch the temperature gauge the whole time, don't let it overheat.

But really if you couldn't figure that out on your own you should probably have it towed.