Please provide the full traceback for your exception in order to help us identify your issue. While the last line of the error message tells us what kind of error you got, the full traceback will tell us which line, and other critical information to solve your problem. Please avoid screenshots so we can copy and paste parts of the message.
A full traceback could look like:
Traceback (most recent call last):
File "my_file.py", line 5, in <module>
add_three("6")
File "my_file.py", line 2, in add_three
a = num + 3
~~~~^~~
TypeError: can only concatenate str (not "int") to str