Angelee, you are in store for multiple days of fun! Hang on to your safety bar because sometimes the many ticket options at Walt Disney World can leave you feeling like you just flipped upside down on Rock 'n' Roller Coaster.
Think of the Water Park Fun and More options as completely separate from your theme park admissions. For example, a six day ticket provides you with six days of theme parks. When you add a Park Hopper, you may visit as many theme parks as many times as you wish for six days. With your Water Park Fun and More add on you are entitled to six admissions, not days, to water parks, golf, and other included activities.
For example, on your first day you hit the Magic Kingdom. On your second day you go splash and play at Disney's Typhoon Lagoon and Disney's Blizzard Beach. You now have five days left of theme park admissions and four admissions remaining on your WPFM. So yes, you may visit two water parks on the same day but you will be using two admissions not park hopping. You may enter and leave the same water park on the same day under only one admission.
Please contact me if you have any additional questions about tickets or any other aspect of planning a Walt Disney World vacation!