(Not Provided) = Organic visits from a keyword search
In 2011 Google switched to a secure server (https) which encrypts search results. Meaning anytime you’re logged into Google (i.e. Gmail, Calendar or YouTube) your searches become protected – Leaving all keyword data as (not provided) in Google Analytics.
We’re noticing most accounts have more than 50% of all keyword information replaced with (not provided).
(Not Set) = A direct visit or a referral from another site
This is a little more complicated, but basically refers to a catch-all for information Google Analytics wasn’t able to identify.
For example, if you see landing page = (not set), it probably means that session didn’t have a page or screen view. The session could have been triggered an Event or an E-commerce hit type.