A positional shot is an approach shot where you are not attempting to hit the green, instead you are intentionally playing into another part of the course. The two typical scenarios where this would occur would be:
1) On a par 5 when you can't reach the green so lay up to a suitable distance for your third shot.
2) If your drive goes into trouble and you need to play out sideways on the second shot.
By marking a shot as "Positional" it will be excluded from the "Approach' "Short Game" and "Club" stats in your performance data which means your stats stay accurate.