Welcome to the forum.
Depending on your level of background, you may want to look into
this thread for some of the basics.e
Specifically for the jib tracks: they allow you to change the angle at which the jib sheet pulls on the clew of the jib. With the cleat moved back along the track, the pull is more horizontal. More tension will be on the foot of the sail compared to the leech.
This allows the top of the sail to blow out, creating twist in the sail. You would choose that in strong winds to depower the sail, but you can also use it in very light winds, because then, the wind direction experienced at different heights above the deck will be different (see "
Basic Concepts and Techniques").
For moderate to moderately strong winds, the jib cleats would be moved forward, so the jib sheet pulls down and helps tension the leech (back edge) of the sail.
You should experiment a bit on the water to see whether you can tell a difference. Don't be disappointed if the differences prove to be a bit subtle. That's not unusual about sail trim -- most people will get better over time and know when a sail looks right.