Just like gears in your car. Sorta...
The pitch number is the number of inches forward the prop will go in one revolution.
Now from there it gets really complicated, diameter, rake, cup, blade design ALL make a difference. And, what runs right on my hull could be totally wrong on yours.
There's some very good experience here, so if you want a good answer, ask the right question:
What exactly you're running now, with details: rpms/speed/lift/holeshot time, the more you give the better you'll get.
Marble Falls/Seadrift TX