The line of best fit tells us a lot about the habits of point guards each year. A line is defined as y=mx+b, where in this case we have: (three points attempted) = m(two points attempted)+b.
In our application, the higher m gets, the more likely point guards that year are to skew towards shooting more threes, given their normal two point shot volume. Whereas b relates to the baseline number of threes a player would attempt if he or she didn’t shot any two point shots. You could then take this analysis further by saying those point guards who fall above the line are your perimeter scorers. Those who prefer to pull up from outside the arc. Whereas those who fall underneath the line tend to take it to the rim, or perhaps run a pick and roll play.