A rectange has four sides. Two sides with the same length and other two sides of the same length.
This means that if you rotate the rectangle you will obtain the same figure only for rotation of 180°.
You can notice the previous conclusion in the following image:
The rectangle with black lines is the original one, and the rectangle with red lines is the rotated rectangle with a rotation of 180°. You can observe that for such a rtation yo obtain the same figure.