The title is something for you to ponder about. When I first heard it, it really struck me as I've not looked at it that way before.
Some things have to be learned and not taught.
You can teach someone how a magic trick is performed but they may never be able to do it, until they've learnt to do it themselves through practice. This also applies to other physical skills such as cycling, dancing, and so on.
When I gave it a little more thought, this statement applies to non-physical skills too. Things such as interpersonal relationship management, how to be a good "mate" in a relationship, learning to cope with failure, or even understanding how to love yourself.
Quite a few of these important skills have to be learnt through experience. There's no running from the pain of blunders so that you learn something new.