‘Including, but not limited to’ is easiest to explain in an example. Like this…
There might be a sign on a park’s gate with a warning like this:
“In this park certain activities are not permitted, including, but not limited to, skateboarding, cycling and ball games.”
The park authorities list some of the things that they don’t allow but, by using “not limited to” they are making it clear that other activities, like car racing or bear-baiting, might be disallowed to.
It wouldn’t be practical, or necessary, to list everything you can’t do in the park, so the authorities pick some important ones and then add the ‘and any other unlisted thing we don’t like‘ in the ‘not limited to’ rider.
People are often unsure about the punctuation of ‘including, but not limited to’.
The expression is clearer if sub-phrase ‘but not limited to’ is bracketed off in some way. Any of these could be used for that:
A. Including, but not limited to, skateboarding, cycling and ball games.
B. Including – but not limited to – skateboarding, cycling and ball games.
C. Including (but not limited to) skateboarding, cycling and ball games.
All of the above convey the meaning and are grammatically correct. B and C are rather clunky though and commas, as in A are perfectly adequate.