A 4-day PH+ allows 4 days of entry to the main theme parks, PLUS 4 entries/admissions (not days) to the waterparks, mini-golf, foot-golf, ESPN or greens fees at Oak Trail golf course.
It does extend the ticket by 1 extra day -- so a 4-day base or PH ticket is valid during a 7-day window (enter a park any 4 days within that period). The PH+ makes it an 8-day window to use all options. You can do a theme park and mini-golf on the same day, or foot golf and a waterpark on the same day, or any combination of 4 theme parks and 4 plus options during that 8-day window. You can mix-and-match as you wish, or do 1 thing each day.