What conjecture can you make about the fourteenth figure in this pattern?

It will be a rectangle with the short side turned vertically (just like the 2nd figure).

Step-by-step explanation:

Every 3rd figure in this pattern is a rectangle with the long side turned vertically.  This means all multiples of 3 will be this way:  3, 6, 9, 12, 15.

This means the figure before the 15th figure, the 14th figure, will be the same as the second figure; that is, a rectangle with the short side turned vertically.

See attached figure for solution(s).