Candito Workout is an app for a 6 week long training program made by Jonnie Candito.
You can read more about the training program on the official website or inside the app.
The main function of the app is to make the program easier to follow. Instead of trying to make excel work on your phone, you can now simply use the app. It will calculate the weights, you can choose optional excercises unlike in excel and some other features.