There has been much confusion about the various lists available on Hive. This post is meant to answer some of your questions to that regard. Please feel free to ask more questions as you see fit.
These are on-chain lists based on the 'follow' function, which allows you to interact by either choosing to view in prominence or to hide from view the posts of another account.
Any user can create a list or subscribe to an existing list that someone else created. When subscribed or created, the list will govern which accounts the user will not see. This is currently widely used for phishing accounts.
List is for limiting interaction with accounts on it
Users and projects are able to create a coherent list of undesirable accounts (in their opinion)
Subscribers can limit what they themselves can see and keep their experienced focused
Lists mainly affect the frontend user experience