I'd say it's not that hard to figure this one out, but really it's something very often overlooked. People will go on to bet on their favorite team usually regardless of odds and won't even do much to adjust their bet size. A smart gambler would adjust his bets based on how risky a certain bet is. However betting blindly will just result in having no advantage and leaving things mostly to luck.
Surely you won't be able to change the outcomes, but by looking at the odds and choosing which bets are more worth than others you're making a choice that in the long term will help achieve better results in terms of performance. Really it's mostly about avoiding certain bets that have bad odds.
As explained in the OP.
A line actually refers to the point spread, or the specific number of points the sportsbook uses to determine the odds between an underdog and a favorite. The line is the margin between those two outcomes.
So that says it's not the betting odds which is known as moneyline when betting on a team to win straight up. We are discussing about the "point spread" here, it's the + - of the game which is harder to predict than just predicting the winner of the game.