Sure! In the given function, division by zero would raise a ZeroDivisionError exception, which is a standard Python error that is raised when attempting to divide a number by zero.

Here's how the code works:
```python
def arithmetic_operation(operator, num1, num2):
    if operator == '+':
        return num1 + num2
    elif operator == '-':
        return num1 - num2
    elif operator == '*':
        return num1 * num2
    elif operator == '/':
        if num2 == 0:
            raise ZeroDivisionError("Cannot divide by zero")
        return num1 / num2
```
When the operator is "/", the code first checks if num2 is equal to zero using the if statement. If num2 is indeed equal to zero, it raises a ZeroDivisionError exception with a custom error message. If num2 is not zero, the function performs the division operation as expected and returns the result.

If you want to handle division by zero differently, you can modify the code in the if statement to return a custom value or perform another action instead of raising an exception.
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