The My Disney Experience will allow you access to things like checking wait times while in the park, checking park hours, character locations, etc. Here’s some other things My Disney Experience does:
It includes complete information about Walt Disney World Resort attractions, experiences, dining and resort hotels, as well as interactive maps, videos, itinerary tools and more.
It also allows you the ability to lock in some of your must-do experiences in advance through FastPass+.
My Disney Experience also allows you to find restaurants (more than 80 to choose from) and make dining reservations
Through the app or website you can also connect with family and friends to coordinate plans and share photos.