What does the Unfollow setting mean?

Boostgram will only ever unfollow the people the software has followed, leaving the people you have followed manually alone. If you would like to unfollow everyone, switch the unfollow setting to "All" and the software will gradually unfollow all of the accounts you follow.

More clearly, under the Unfollow Settings on your Boostgram Dashboard:

Boostgram = Unfollow only people the software has followed.
All = Unfollow everyone that the account currently follows.

The Time Until Unfollow setting is the time delay between when Boostgram follows an account to when it automatically unfollows it. We generally see the best results with a delay setting of 1 day, however some people like to maintain their feed so they prefer the 1 hour setting.