i dont understand how can I put an amount in these letters?

You can try something with Using Dictionary:

Using Dictionary code is more more readable and less if else condition

totalBought = float(input("how much you bought in total:"))
discountDict ={
     'S':10,
     'O': 5,
     'M':15,
     'E':20

}
discountAmt = input("what is your status:")


totalPrice = totalBought - discountDict[discountAmt]

print(totalPrice)

On the second line, discountAmt is assigned a string value. That string value remains its value throughout the code. And so when you do totalBought - discountAtm, you do a number minus a string, which doesn't make sense. Also, you need to distinguish between == and =. What you can do is replace all those S == 10, O == 5, etc. with discoutAmt = 10, discountAmt = 5, etc. Or, you can dedicate a separate variable to the discount amount, if you don't want to override the discount code.

First of all, you are using == which returns a boolean, use = to assign a variable. Secondly, no need to create different variables. Just use one S to assign discounts.

Refer to the solution below:

totalBought = float(input("how much you bought in total:")) 
discountAmt = input("what is your status:")

if discountAmt == "S":
    S = 10
elif discountAmt == "O":
    S = 5
elif discountAmt == "M":
    S = 15
elif discountAmt == "E":
    S = 20

totalPrice = totalBought - S
print(totalPrice)