The perimeter for a rectangle is the total distance around it.
the distance from C to D is 6 units.
The distance from D to A is 5 units
The distance from A to B is 6 units
The distance from B to C is 5 units
Therefore the perimeter of the rectangle ABCD is
6+5+6+5
11+11=22
Therefore the perimeter of this shape is 22 units