Toni put it about as simple and as perfect as you can get. It's worth repeating:
"By picking value, value is when you think the odds are wrong in your favor."
Only 1% of people who bet on sports do so profitably. This is EXACTLY what these people are looking for. They study the players, the statistics, the conditions, the teams, and ESPECIALLY the lines.
Think about this - let's say someone was SO perfect at sports handicapping that they were extremely confident that Team X would beat Team Y by 3 points. Well if the line says -3 for Team X, then they should NOT place a bet on that game! If they find a line that says -4 for Team X, then they should place a bet on Team Y. If they find a line that says -2 for Team X, then they should bet on Team X.
The most important point I'd like to leave you with is that "1%" I mentioned. Odds are that you are NOT one of these people. Most likely if you continue to bet, you will lose in the long run.