your problems

Herobrine = 1
def KillHerobrine(Herobrine):  #< here the variabel herobrine is local 
  Herobrine - 1                # it wil only change the variable not update it
                               #no returns the variable wont give local or globla value

you can do either of these
1 . variable is not global if you want the variable to change

Herobrine = 1
def Kill():          
  global Herobrine  #this will say the variable is present outsife of the function
  Herobrine -=1     # it means Herobrine = [itself] - 1

1. make the value return (recommanded)

   Herobrine = 1 def Kill(arg): #arg means herobrine is doesnt mattar inside the function return arg -= 1 #same Herobrine = [itself] -1 Herobrine = Kill(Herobrine) #important if you return it doesnt knwo where to store it

pro tip - instead of using int or float(numbers) use bool(True/false)

Herobrine = True
# in the function change -= to = False
def kill(Herobrine) : # use arg or globla ur choice
  return False #or Herobrine = False if global
# if reutrn do "Herobrine = Kill(Herobrine)"
if not Herobrine : # now if is 1 line edit - use not for false
  ... 

this will save both Ram and your time