The vertex order has been reversed, so a reflection is involved. The direction of the short side has been changed by 90°, so a rotation is potentially involved. Depending on the precise rotation and/or reflections, translation may be involved.
One potential set of transformations is ...
rotate 90° CW about the origin
translate left 1 and down 3
reflect across the y-axis
Another potential set of transformations (shown below) is ...