When placing a bet on "Final Result (in sets - best of 3)", you are betting on exactly how many sets each player will win. For example:
Sam Querrey v Brian Dabul (Final Result (in sets - best of 3))
2:0
This bet indicates that Sam Querry (the first player listed) will win exactly 2 sets and Brian Dabul (the second player listed) will win exactly 0 sets.
If you wanted to bet on Brian Dabul to beat Sam Querry 2 sets to 1, then you would need to place the following bet:
Sam Querrey v Brian Dabul (Final Result (in sets - best of 3))