Moneyline is on the straight up outcome of the game. Iowa +200 means that Iowa is the underdog (because you're getting paid more on Iowa winning). In this case you have to bet $100 to win $200. Conversely a -200 money line means you have to bet $200 to win $100. TL;DR moneyline is straight up; negative numbers show how much you have to bet to win $100; positive numbers show how much you win on a $100 bet.
This applies similarly to the point spread. You would have to bet $115 on either team to cover the spread to win $100. Or you would have to be bet $120 to win $100 to play the over/under.
This is all just a way for the house to manage odds and risk across their offering portfolio. It's similar to the house edge in slots, blackjack, or roulette. Mathematically it means the house will always win in the long run.
