What does it mean?

Question

except Exception as ex: ...

Answer 1

It's called catching an exception.
Every exception in Python inherits from the base Exception class.
except Exception as ex:
means you are catching whatever Exception was raised by the try block and renaming it as ex. You can rename it anything.
except Exception as e:
except Exception as err:
Then you can print it, log it or handle different exceptions in whatever way you want.

Answer 2

try:
print(undefinedVariable)
except Exception as somevar:
print(somevar)

Output is the exception: name undefinedVariable is not declared

Answer 3

https://docs.python.org/3/tutorial/errors.html

8.3 might be, what you are looking for

Answer 4

Bob_Li thx