Author JD Lee says in his book, Inorganic Chemistry
The dipole moment of $\ce{XeF6}$ is approximately = $0$ because the lone pair is present in the stereochemically inactive s orbital.
What is this stereochemically inactive s orbital? What does the statement mean?
PS: Please don't provide links to any web pages as I have gone crazy by the definitions they provide and also please try to explain it in an easy language and not some very technical chemistry as I am not an expert.