at first you have to be aware that Python is only available in CoDeSys V3. Probably most of the devices you have mentioned still work with CoDeSys V2.3. CoDeSys V3 is not downward compatible, thus you will not be able to benefit from Python inside CoDeSys.
In order to get an idea how Python can help you could check the examples under http://forum-en.3s-software.com/viewtopic.php?f=18&t=1906
In general as already mentioned Python is useful for automatically executing commands of the development environment, such as
import POU xxx
set communication to device xxx
download the application
write certain values to certain variables
(of course this is a rough abstraction of the code
Imagine you have to do that exactly in the same way for several time, e.g. at a series of machines with the same application and PLC (which are not connected in one single network) - with a Python script you could execute the whole batch of commands with one click (and without becoming crazy after the 10th repetition...
I hope this will help you to have an idea how Python can accelerate your work.