You have the line segment PQ shown in the exercise. Notice that you must copy the length of that line using the compass. Notice that one of the endpoints of the new line is R.
In order to copy it, you can follow these steps:
1. You need to place the compass on one of the endpoints of the line PQ.
2. Open the compass to the length of the segment PQ (one leg of the compass must be on the endpoint P and the other one on the endpoint Q).
3. Using the amount of opening found in the previous step, place the compass on the point R and make a mark with the other leg of the compass.
Notice that by applying these steps, you get a segment with the same length of PQ.
Therefore, the answer is: