Function for beginner. Could you help me find out what is wrong with the code

def arithmetic(a,b,operation):
    if operation =="+" or "-":
        return False
    elif operation=="**" or "*":
        return False
        return "Unknown operation"


I want to help.

For my benefit, can you please explain what you are trying to accomplish with this code.
I see what starts out as a definition of a function, arithmetic(). I also see what appears to be 2 calls to the function. The problem?
[1] As written, these calls to the function are not properly indented and therefore appear to be part of the function. Python is very specific that they need to be. (I understand that you may have had difficulties in properly posting your code to the forum.)
[2] Even if the calls were properly indented, their results will be displayed. You need print() statements for that – if you are using Python 3.

I am curious … which IDE (or text editor) are you using? A good IDE will give you some clues about what is not right when you execute what you wrote.

What is your code doing that is not what you expect?

In the code above, which is the code below the return statement, will never run because the return statement will cause the function to exit.