Her are the basics of fletchings.

The longer it is the more air it "grabs" and the more stabil it is.

The more helical the fletching has the more spin it gives the arrow. Which the faster the arrow spins the more gyroscopic effect the arrow has and the more stabil it becomes. It is much harder to introduce outside forces to a spinning object than it is an object that is stationary.

The lighter weight the fletching the less the end of the arrow weighs and the better the fletching can control the end of the arrow. The more mass the harder it is for the fletching to correct any flight problems.