Okurr, let's break it down for you:
Funds - This is the total amount of money coming into your bank account which includes your salary and your bank balance.
Bills - Bills will show all of your bills that are due within the given paycycle.
Spending - This shows a breakdown of your estimated spending per-category throughout your paycycle, if the numbers don't look right, you can always edit them and keep track of your spending against the paycycle planned amount :)
Leftover - This shows how much money we expect to be leftover in your bank at the end of your paycycle.